diff --git a/_test/mock/AuthCreatePlugin.php b/_test/mock/AuthCreatePlugin.php
deleted file mode 100644
index 38d93a1a8..000000000
--- a/_test/mock/AuthCreatePlugin.php
+++ /dev/null
@@ -1,36 +0,0 @@
-<?php
-
-namespace dokuwiki\test\mock;
-
-/**
- * Class dokuwiki\Plugin\DokuWiki_Auth_Plugin
- */
-class AuthCreatePlugin extends AuthPlugin {
-
-    public $loggedOff = false;
-
-    /** @var array user cache */
-    protected $users = null;
-
-    public function __construct($canAddUser = true) {
-        $this->cando['addUser'] = $canAddUser;
-    }
-
-    public function checkPass($user, $pass) {
-        return $pass == 'password';
-    }
-
-    public function createUser($user, $pwd, $name, $mail, $grps = null) {
-        if (isset($this->users[$user])) {
-            return false;
-        }
-        $pass = md5($pwd);
-        $this->users[$user] = compact('pass', 'name', 'mail', 'grps');
-        return true;
-    }
-
-    public function logoff() {
-        $this->loggedOff = true;
-    }
-
-}
diff --git a/_test/tests/Remote/ApiCoreCreateUserTest.php b/_test/tests/Remote/ApiCoreCreateUserTest.php
deleted file mode 100644
index cffeac06c..000000000
--- a/_test/tests/Remote/ApiCoreCreateUserTest.php
+++ /dev/null
@@ -1,193 +0,0 @@
-<?php
-
-namespace dokuwiki\test\Remote;
-
-use dokuwiki\Remote\AccessDeniedException;
-use dokuwiki\Remote\Api;
-use dokuwiki\Remote\RemoteException;
-use dokuwiki\test\mock\AuthCreatePlugin;
-use dokuwiki\test\mock\AuthPlugin;
-
-/**
- * Class remoteapicore_test
- */
-class ApiCoreCreateUserTest extends \DokuWikiTest
-{
-
-    protected $userinfo;
-    protected $oldAuthAcl;
-    /** @var  Api */
-    protected $remote;
-
-    public function setUp(): void
-    {
-        // we need a clean setup before each single test:
-        \DokuWikiTest::setUpBeforeClass();
-
-        parent::setUp();
-        global $conf;
-        global $USERINFO;
-        global $AUTH_ACL;
-        global $auth;
-        $this->oldAuthAcl = $AUTH_ACL;
-        $this->userinfo = $USERINFO;
-        $auth = new AuthPlugin();
-
-        $conf['remote'] = 1;
-        $conf['remoteuser'] = '@user';
-        $conf['useacl'] = 0;
-
-        $this->remote = new Api();
-    }
-
-    public function tearDown(): void
-    {
-        parent::tearDown();
-
-        global $USERINFO;
-        global $AUTH_ACL;
-
-        $USERINFO = $this->userinfo;
-        $AUTH_ACL = $this->oldAuthAcl;
-    }
-
-    public function testCreateUser()
-    {
-        global $conf, $auth;
-        $conf['remote'] = 1;
-        $conf['remoteuser'] = 'testuser';
-        $_SERVER['REMOTE_USER'] = 'testuser';
-
-        $auth = new AuthCreatePlugin();
-        // $user, $pwd, $name, $mail, $grps = null
-        $params = [
-            [
-                'user' => 'user1',
-                'password' => 'password1',
-                'name' => 'user1',
-                'mail' => 'user1@localhost',
-                'groups' => [
-                    'user',
-                    'test'
-                ],
-                'notify' => false
-            ]
-        ];
-
-        $actualCallResult = $this->remote->call('dokuwiki.createUser', $params);
-        $this->assertTrue($actualCallResult);
-
-        // if the user exists, no data is overwritten
-        $actualCallResult = $this->remote->call('dokuwiki.createUser', $params);
-        $this->assertFalse($actualCallResult);
-    }
-
-    public function testCreateUserAuthPlain()
-    {
-        global $conf, $auth;
-        $conf['remote'] = 1;
-        $conf['remoteuser'] = 'testuser';
-        $_SERVER['REMOTE_USER'] = 'testuser';
-        $auth = new \auth_plugin_authplain();
-        $params = [
-            [
-                'user' => 'user1',
-                'password' => 'password1',
-                'name' => 'user1',
-                'mail' => 'user1@localhost',
-                'groups' => [
-                    'user',
-                    'test'
-                ],
-                'notify' => false
-            ]
-
-        ];
-
-        $callResult = $this->remote->call('dokuwiki.createUser', $params);
-        $this->assertTrue($callResult);
-    }
-
-    public function testCreateUserAuthPlainUndefinedUser()
-    {
-        global $conf, $auth;
-        $conf['remote'] = 1;
-        $conf['remoteuser'] = 'testuser';
-        $_SERVER['REMOTE_USER'] = 'testuser';
-        $auth = new \auth_plugin_authplain();
-        $params = [
-            [
-                'user' => ''
-            ],
-        ];
-
-        $this->expectException(RemoteException::class);
-        $this->expectExceptionCode(401);
-        $this->remote->call('dokuwiki.createUser', $params);
-    }
-
-    public function testCreateUserAuthPlainUndefinedName()
-    {
-        global $conf, $auth;
-        $conf['remote'] = 1;
-        $conf['remoteuser'] = 'testuser';
-        $_SERVER['REMOTE_USER'] = 'testuser';
-        $auth = new \auth_plugin_authplain();
-        $params = [
-            [
-                'user' => 'hello'
-            ],
-        ];
-
-        $this->expectException(RemoteException::class);
-        $this->expectExceptionCode(402);
-        $this->remote->call('dokuwiki.createUser', $params);
-    }
-
-    public function testCreateUserAuthPlainBadEmail()
-    {
-        global $conf, $auth;
-        $conf['remote'] = 1;
-        $conf['remoteuser'] = 'testuser';
-        $_SERVER['REMOTE_USER'] = 'testuser';
-        $auth = new \auth_plugin_authplain();
-        $params = [
-            [
-                'user' => 'hello',
-                'name' => 'A new user',
-                'mail' => 'this is not an email address'
-            ],
-        ];
-
-        $this->expectException(RemoteException::class);
-        $this->expectExceptionCode(403);
-        $this->remote->call('dokuwiki.createUser', $params);
-    }
-
-    public function testCreateUserAuthCanNotDoAddUser()
-    {
-        $this->expectException(AccessDeniedException::class);
-        $this->expectExceptionMessageMatches('/can\'t do addUser/');
-        global $conf, $auth;
-        $conf['remote'] = 1;
-        $conf['remoteuser'] = 'testuser';
-        $_SERVER['REMOTE_USER'] = 'testuser';
-
-        $auth = new AuthCreatePlugin(false);
-        $params = [
-            [
-                'user' => 'user1',
-                'password' => 'password1',
-                'name' => 'user1',
-                'mail' => 'user1@localhost',
-                'groups' => [
-                    'user',
-                    'test'
-                ],
-                'notify' => false
-            ],
-        ];
-        $this->remote->call('dokuwiki.createUser', $params);
-    }
-
-}
diff --git a/_test/tests/Remote/ApiCoreTest.php b/_test/tests/Remote/ApiCoreTest.php
index 1f57f8483..7da1007e0 100644
--- a/_test/tests/Remote/ApiCoreTest.php
+++ b/_test/tests/Remote/ApiCoreTest.php
@@ -2,12 +2,10 @@
 
 namespace dokuwiki\test\Remote;
 
-use dokuwiki\Extension\Event;
 use dokuwiki\Remote\AccessDeniedException;
 use dokuwiki\Remote\Api;
 use dokuwiki\Remote\ApiCore;
 use dokuwiki\Remote\RemoteException;
-use dokuwiki\test\mock\AuthDeletePlugin;
 use dokuwiki\test\mock\AuthPlugin;
 
 
diff --git a/lib/plugins/usermanager/_test/AuthPlugin.php b/lib/plugins/usermanager/_test/AuthPlugin.php
new file mode 100644
index 000000000..99805fa8c
--- /dev/null
+++ b/lib/plugins/usermanager/_test/AuthPlugin.php
@@ -0,0 +1,54 @@
+<?php
+
+namespace dokuwiki\plugin\usermanager\test;
+
+/**
+ * Simple Auth Plugin for testing
+ *
+ * All users are stored in a simple array
+ * @todo This might be useful for other tests and could replace the remaining mock auth plugins
+ */
+class AuthPlugin extends \dokuwiki\Extension\AuthPlugin {
+
+    public $loggedOff = false;
+
+    /** @var array user storage */
+    public $users = [];
+
+    /** @inheritdoc */
+    public function __construct($cando = []) {
+        parent::__construct(); // for compatibility
+
+        // our own default capabilities
+        $this->cando['addUser'] = true;
+        $this->cando['delUser'] = true;
+
+        // merge in given capabilities for testing
+        $this->cando = array_merge($this->cando, $cando);
+    }
+
+    /** @inheritdoc */
+    public function createUser($user, $pwd, $name, $mail, $grps = null) {
+        if (isset($this->users[$user])) {
+            return false;
+        }
+        $pass = md5($pwd);
+        $grps = (array) $grps;
+        $this->users[$user] = compact('pass', 'name', 'mail', 'grps');
+        return true;
+    }
+
+    /** @inheritdoc */
+    public function deleteUsers($users)
+    {
+        $deleted = 0;
+        foreach ($users as $user) {
+            if (isset($this->users[$user])) {
+                unset($this->users[$user]);
+                $deleted++;
+            }
+
+        }
+        return $deleted;
+    }
+}
diff --git a/lib/plugins/usermanager/_test/RemoteApiTest.php b/lib/plugins/usermanager/_test/RemoteApiTest.php
new file mode 100644
index 000000000..d24b34dbe
--- /dev/null
+++ b/lib/plugins/usermanager/_test/RemoteApiTest.php
@@ -0,0 +1,241 @@
+<?php
+
+namespace dokuwiki\plugin\usermanager\test;
+
+use dokuwiki\Remote\AccessDeniedException;
+use dokuwiki\Remote\Api;
+use dokuwiki\Remote\RemoteException;
+use DokuWikiTest;
+
+/**
+ * Remote API tests for the usermanager plugin
+ *
+ * @group plugin_usermanager
+ * @group plugins
+ */
+class RemoteApiTest extends DokuWikiTest
+{
+    /** @var  Api */
+    protected $remote;
+
+    public function __construct()
+    {
+        parent::__construct();
+        $this->remote = new Api();
+    }
+
+    public function setUp(): void
+    {
+        parent::setUp();
+
+        global $conf;
+        $conf['remote'] = 1;
+        $conf['remoteuser'] = 'testuser, admin';
+        $conf['superuser'] = 'admin';
+    }
+
+    public function testCreateUserSuccess()
+    {
+        global $auth;
+        $auth = new AuthPlugin();
+
+        $params = [
+            'user' => 'user1',
+            'password' => 'password1',
+            'name' => 'user one',
+            'mail' => 'user1@localhost',
+            'groups' => [
+                'user',
+                'test'
+            ],
+            'notify' => false
+        ];
+
+        $_SERVER['REMOTE_USER'] = 'admin';
+        $this->assertTrue(
+            $this->remote->call('plugin.usermanager.createUser', $params)
+        );
+        $this->assertArrayHasKey('user1', $auth->users);
+
+        // try again should fail, because user already exists
+        $this->assertFalse(
+            $this->remote->call('plugin.usermanager.createUser', $params)
+        );
+    }
+
+    public function testCreateUserFailAccess()
+    {
+        global $auth;
+        $auth = new AuthPlugin();
+
+        $params = [
+            'user' => 'user1',
+            'password' => 'password1',
+            'name' => 'user one',
+            'mail' => 'user1@localhost',
+            'groups' => [
+                'user',
+                'test'
+            ],
+            'notify' => false
+        ];
+
+        $_SERVER['REMOTE_USER'] = 'testuser';
+
+        $this->expectException(AccessDeniedException::class);
+        $this->expectExceptionCode(114);
+        $this->remote->call('plugin.usermanager.createUser', $params);
+    }
+
+    public function testCreateUserFailMissingUser()
+    {
+        global $auth;
+        $auth = new AuthPlugin();
+
+        $params = [
+            'user' => '',
+            'password' => 'password1',
+            'name' => 'user one',
+            'mail' => 'user1@localhost',
+            'groups' => [
+                'user',
+                'test'
+            ],
+            'notify' => false
+        ];
+
+        $_SERVER['REMOTE_USER'] = 'admin';
+
+        $this->expectException(RemoteException::class);
+        $this->expectExceptionCode(401);
+        $this->remote->call('plugin.usermanager.createUser', $params);
+    }
+
+    public function testCreateUserFailMissingName()
+    {
+        global $auth;
+        $auth = new AuthPlugin();
+
+        $params = [
+            'user' => 'user1',
+            'password' => 'password1',
+            'name' => '',
+            'mail' => 'user1@localhost',
+            'groups' => [
+                'user',
+                'test'
+            ],
+            'notify' => false
+        ];
+
+        $_SERVER['REMOTE_USER'] = 'admin';
+
+        $this->expectException(RemoteException::class);
+        $this->expectExceptionCode(402);
+        $this->remote->call('plugin.usermanager.createUser', $params);
+    }
+
+    public function testCreateUserFailBadEmail()
+    {
+        global $auth;
+        $auth = new AuthPlugin();
+
+        $params = [
+            'user' => 'user1',
+            'password' => 'password1',
+            'name' => 'user one',
+            'mail' => 'This is not an email',
+            'groups' => [
+                'user',
+                'test'
+            ],
+            'notify' => false
+        ];
+
+        $_SERVER['REMOTE_USER'] = 'admin';
+
+        $this->expectException(RemoteException::class);
+        $this->expectExceptionCode(403);
+        $this->remote->call('plugin.usermanager.createUser', $params);
+    }
+
+    public function testCreateUserFailAuthCapability()
+    {
+        global $auth;
+        $auth = new AuthPlugin(['addUser' => false]);
+
+        $params = [
+            'user' => 'user1',
+            'password' => 'password1',
+            'name' => 'user one',
+            'mail' => 'user1@localhost',
+            'groups' => [
+                'user',
+                'test'
+            ],
+            'notify' => false
+        ];
+
+        $_SERVER['REMOTE_USER'] = 'admin';
+
+        $this->expectException(AccessDeniedException::class);
+        $this->expectExceptionCode(404);
+        $this->expectExceptionMessageMatches('/can\'t do addUser/');
+        $this->remote->call('plugin.usermanager.createUser', $params);
+    }
+
+    public function testDeleteUserSuccess()
+    {
+        global $auth;
+        $auth = new AuthPlugin();
+        $auth->users = [
+            'user1' => [
+                'pass' => 'password1',
+                'name' => 'user one',
+                'mail' => 'user1@localhost',
+                'grps' => [
+                    'user',
+                    'test'
+                ]
+            ],
+            'user2' => [
+                'pass' => 'password2',
+                'name' => 'user two',
+                'mail' => 'user2@localhost',
+                'grps' => [
+                    'user',
+                    'test'
+                ]
+            ],
+        ];
+
+        $_SERVER['REMOTE_USER'] = 'admin';
+
+        $this->assertTrue($this->remote->call('plugin.usermanager.deleteUser', ['user' => 'user1']));
+        $this->assertArrayNotHasKey('user1', $auth->users);
+        $this->assertArrayHasKey('user2', $auth->users);
+    }
+
+    public function testDeleteUserFailNoExist()
+    {
+        global $auth;
+        $auth = new AuthPlugin();
+
+        $_SERVER['REMOTE_USER'] = 'admin';
+
+        $this->assertFalse($this->remote->call('plugin.usermanager.deleteUser', ['user' => 'user1']));
+    }
+
+    public function testDeleteUserFailAuthCapability()
+    {
+        global $auth;
+        $auth = new AuthPlugin(['delUser' => false]);
+
+        $_SERVER['REMOTE_USER'] = 'admin';
+
+        $this->expectException(AccessDeniedException::class);
+        $this->expectExceptionCode(404);
+        $this->expectExceptionMessageMatches('/can\'t do delUser/');
+        $this->remote->call('plugin.usermanager.deleteUser', ['user' => 'user1']);
+    }
+}
diff --git a/lib/plugins/usermanager/remote.php b/lib/plugins/usermanager/remote.php
index 5db4a54f9..c2b61f361 100644
--- a/lib/plugins/usermanager/remote.php
+++ b/lib/plugins/usermanager/remote.php
@@ -46,7 +46,7 @@ class remote_plugin_usermanager extends RemotePlugin
         if (!$auth->canDo('addUser')) {
             throw new AccessDeniedException(
                 sprintf('Authentication backend %s can\'t do addUser', $auth->getPluginName()),
-                114
+                404
             );
         }
 
@@ -62,7 +62,7 @@ class remote_plugin_usermanager extends RemotePlugin
             try {
                 $password = auth_pwgen($user);
             } catch (\Exception $e) {
-                throw new RemoteException('Could not generate password', 404); // FIXME adjust code
+                throw new RemoteException('Could not generate password', 405);
             }
         }
 
@@ -95,6 +95,15 @@ class remote_plugin_usermanager extends RemotePlugin
         if (!auth_isadmin()) {
             throw new AccessDeniedException('Only admins are allowed to delete users', 114);
         }
+
+        global $auth;
+        if (!$auth->canDo('delUser')) {
+            throw new AccessDeniedException(
+                sprintf('Authentication backend %s can\'t do delUser', $auth->getPluginName()),
+                404
+            );
+        }
+
         /** @var AuthPlugin $auth */
         global $auth;
         return (bool)$auth->triggerUserMod('delete', [[$user]]);