docs: function(id, callback) {
          /**
           * Callback for QB.pushnotifications.subscriptions.delete(id, callback)
           * @callback deletePushSubscriptionCallback
           * @param {object} error - The error object
           * @param {object} response - Empty body
           */
          var attrAjax = {
              'type': 'DELETE',
              'dataType': 'text',
              'url': Utils.getUrl(config.urls.subscriptions, id)
          };
  
          this.service.ajax(attrAjax, function(err, res){
              if (err) {
                  callback(err, null);
              } else {
                  callback(null, true);
              }
          });
      }