async function destroy(selector) {
  const user = await db.User.findOne({
    where: {
      selector,
    },
  });
  if (user === null) {
    throw new NotFoundError('User not found');
  }
  await user.destroy();
  this.stateManager.deleteState('user', user.selector);
}
@private
@description This function delete a user in DB and in state.
@name gladys.user.getById
@param {string} selector - The selector of the user.
@returns {Promise} Promise.
@example
await gladys.user.destroy('tony');