core_courses_delete_courses don't work

I created one app for delete course with REST but the function 'core_courses_delete_courses' don't work.

My code is this:

require_once(dirname(__FILE__) . '/rest/MoodleRest.php');

$MoodleRest = new MoodleRest('mysite/webservice/rest/server.php', tokenmoodle);
$delete_course = array('courseids' => array(7));
$return = $MoodleRest->request('core_courses_delete_courses', $delete_course, MoodleRest::METHOD_POST);

HELP