deleteCronQuery (key, userId) {
    return new Promise((resolve, reject) => {
      const options = {
        method: 'DELETE',
        params: { userId },
        url: `api/cron/${key}`
      };

      Vue.axios(options).then((response) => {
        resolve(response.data);
      }).catch((error) => {
        reject(error);
      });
    });
  }
Deletes a user's specified cron query
@param {string} key        The key of the cron query to be removed
@param {string} userId     The unique identifier for a user
                           (only required if not the current user)
@returns {Promise} Promise A promise object that signals the completion
                           or rejection of the request.