Deleting an existing subscription
        :param subscription_id: is the subscription the client wants to delete

def delete_subscription(self, subscription_id):
        """
        Deleting an existing subscription
        :param subscription_id: is the subscription the client wants to delete
        """
        self._validate_uuid(subscription_id)

        url = "/notification/v1/subscription/{}".format(subscription_id)
        response = NWS_DAO().deleteURL(url, self._write_headers())

        if response.status != 204:
            raise DataFailureException(url, response.status, response.data)

        return response.status