code: function(params, callback) {
          /**
           * Callback for QB.users.delete(params, callback)
           * @callback deleteUserCallback
           * @param {object} error - The error object
           * @param {object} response - Empty body
           */
          var url;
  
          if (typeof params === 'number') {
              url = params;
          } else {
              if (params.external) {
                  url = 'external/' + params.external;
              }
          }
  
          this.service.ajax({url: Utils.getUrl(config.urls.users, url), type: 'DELETE', dataType: 'text'}, callback);
      }
docs: Remove a user from the app, {@link https://docsdev.quickblox.com/rest_api/Users_API.html#Delete_user_by_id by user's id} or {@link https://docsdev.quickblox.com/rest_api/Users_API.html#Delete_user_by_external_user_id uid that represents the user in an external user registry}
  @memberof QB.users
  @param {(number|object)} params - An id of user to remove or object with external user id
  @param {(number|string)} params.external - An id of user to remove or object with external user id
  @param {deleteUserCallback} callback - An uid that represents the user in an external user registry
  @example
  // parameter as user id:
  var params = 567831;
  
  // parameter as external user id:
  // var params = {'external': 'ebdf831abd12da4bcf12f22d'};
  
  QB.users.delete(params, function(error, response) {
  if (error) {
  console.log(error);
  } else {
  console.log(response);
  }
  });