protected function removePermission($name)
    {
        $permission = $this->authManager->getPermission($name);
        if (empty($permission)) {
            throw new InvalidParamException("Permission '{$permission}' does not exists");
        }
        echo "    > removing permission $permission->name ...";
        $time = microtime(true);
        $this->authManager->remove($permission);
        echo ' done (time: ' . sprintf('%.3f', microtime(true) - $time) . "s)\n";
    }