auctions-1.0.x-dev/modules/auctions_mail/auctions_mail.install

<?php

/**
 * @file
 * Contains auctions_core.module.
 */

/**
 * Implements hook_uninstall() for the Auctions Mail module.
 *
 * Removes the configuration related to the module during uninstallation.
 */
function auctions_mail_uninstall() {
  // Remove the general confs this module uses.
  \Drupal::configFactory()->getEditable('auctions_mail.content')->delete();
}