deleteNotifier (id) {
    return new Promise((resolve, reject) => {
      Vue.axios.delete(`api/notifier/${id}`).then((response) => {
        resolve(response.data);
      }).catch((error) => {
        reject(error);
      });
    });
  }
Deletes a notifier
@param {String} id - The id of the notifier to delete
@returns {Promise} Promise - A promise object that signals the completion
                             or rejection of the request.