deleteUser(workspaceId) {
    return new Promise((resolve, reject) => {
      this.db.run(
        `DELETE FROM users WHERE workspaceId = '${workspaceId}';`,
        (err) => {
          if (err) {
            console.error(err.message);
            reject();
          }
          resolve();
        },
      );
    });
  }
Delete a user from the users table.
@param {string} workspaceId The workspaceId of the user to be removed from
the users table.
@returns {!Promise} Promise object represents the success of the deletion.
@public