public function revokePermissions($accessLevel)
    {
        // Do not revoke the permissions if we haven't all data
        if ($accessLevel == '') {
            return false;
        }
    
        try {
            $em = $this->entityManager->getDoctrineEntityManager();
            $permissions = $em->getRepository('\\Zepi\\Core\\AccessControl\\Entity\\Permission')->findBy(array(
                'accessLevelKey' => $accessLevel
            ));
            
            foreach ($permissions as $permission) {
                $em->remove($permission);
            }
            $em->flush();
        } catch (\Exception $e) {
            throw new Exception('Cannot revoke the access levels "' . $accessLevel . '".', 0, $e);
        }
    }