public function unregister($name = null, $namespace = false)
    {
        if (null === $name) {
            $name = $this->getName();
        }

        $url = UrlHelper::buildUrl(Urls::URL_AQL_USER_FUNCTION, [$name]);

        if ($namespace) {
            $url = UrlHelper::appendParamsUrl($url, ['group' => true]);
        }

        $response = $this->_connection->delete($url);

        return $response->getJson();
    }