module - How to remove a Backend Modul of the Backend Menu in Contao

Question

I developed an modul for contao 3.0. In my config.php file i wrote this lines:

$GLOBALS['BE_MOD']['content']['modultest'] = array(
'tables' => array('tl_modultest'),
'icon'       => 'system/modules/modultest/time_go.png',

);

Now i have the problem, that i want to deinstall the modul. But the menupoint in the backend is still there, even if i deleted the lines above.

Can anybody help me to deactivate or delete deactivated or deinstalled modules from the backend menu ?