Remove a key-value store entry.

        :param key: string

def remove_kv_store(self, key):
        """Remove a key-value store entry.

        :param key: string
        """
        data = {
            'operation': 'DELETE',
            'key': key
        }
        return self.post(self.make_url("/useragent-kv"), data=to_json(data),
                         headers=self.default_headers).text