Delete the item from storage

        :param method callback: The callback method to invoke when done

def delete(self):
        """Delete the item from storage

        :param method callback: The callback method to invoke when done

        """
        result = yield gen.Task(RedisSession._redis_client.delete, self._key)
        LOGGER.debug('Deleted session %s (%r)', self.id, result)
        self.clear()
        raise gen.Return(result)