def delete_webhook(self, scaling_group, policy, webhook):
        """
        Deletes the specified webhook from the specified policy.
        """
        uri = "/%s/%s/policies/%s/webhooks/%s" % (self.uri_base,
                utils.get_id(scaling_group), utils.get_id(policy),
                utils.get_id(webhook))
        resp, resp_body = self.api.method_delete(uri)
        return None
Deletes the specified webhook from the specified policy.