/**
 * Implements hook_user_cancel_methods_alter().
 */
function {{ machine_name }}_user_cancel_methods_alter(&$methods) {
  $account = \Drupal::currentUser();
  // Limit access to disable account and unpublish content method.
  $methods['user_cancel_block_unpublish']['access'] = $account->hasPermission('administer site configuration');

  // Remove the content re-assigning method.
  unset($methods['user_cancel_reassign']);

  // Add a custom zero-out method.
  $methods['mymodule_zero_out'] = [
    'title' => t('Delete the account and remove all content.'),
    'description' => t('All your content will be replaced by empty strings.'),
    // access should be used for administrative methods only.
    'access' => $account->hasPermission('access zero-out account cancellation method'),
  ];
}