public static function delete($app_id, $service_slug, $id)
 {
     WpakWebServiceContext::$crud_action = 'delete';
     $service_answer = array();
     $service_answer = apply_filters('wpak_delete_' . $service_slug, $service_answer, $id, $app_id);
     $service_answer = apply_filters('wpak_delete', $service_answer, $service_slug, $id, $app_id);
     return $service_answer;
 }