Unregister a callback.

        Unregisters a callback URL that was previously white-listed with a **Register a
        callback** request for use with the asynchronous interface. Once unregistered, the
        URL can no longer be used with asynchronous recognition requests.
        **See also:** [Unregistering a callback
        URL](https://cloud.ibm.com/docs/services/speech-to-text/async.html#unregister).

        :param str callback_url: The callback URL that is to be unregistered.
        :param dict headers: A `dict` containing the request headers
        :return: A `DetailedResponse` containing the result, headers and HTTP status code.
        :rtype: DetailedResponse

def unregister_callback(self, callback_url, **kwargs):
        """
        Unregister a callback.

        Unregisters a callback URL that was previously white-listed with a **Register a
        callback** request for use with the asynchronous interface. Once unregistered, the
        URL can no longer be used with asynchronous recognition requests.
        **See also:** [Unregistering a callback
        URL](https://cloud.ibm.com/docs/services/speech-to-text/async.html#unregister).

        :param str callback_url: The callback URL that is to be unregistered.
        :param dict headers: A `dict` containing the request headers
        :return: A `DetailedResponse` containing the result, headers and HTTP status code.
        :rtype: DetailedResponse
        """

        if callback_url is None:
            raise ValueError('callback_url must be provided')

        headers = {}
        if 'headers' in kwargs:
            headers.update(kwargs.get('headers'))
        sdk_headers = get_sdk_headers('speech_to_text', 'V1',
                                      'unregister_callback')
        headers.update(sdk_headers)

        params = {'callback_url': callback_url}

        url = '/v1/unregister_callback'
        response = self.request(
            method='POST',
            url=url,
            headers=headers,
            params=params,
            accept_json=False)
        return response