/**
 * Implements hook_user_cancel().
 */
function {{ machine_name }}_user_cancel($edit, UserInterface $account, $method) {
  switch ($method) {
    case 'user_cancel_block_unpublish':
      // Unpublish nodes (current revisions).
      module_load_include('inc', 'node', 'node.admin');
      $nodes = \Drupal::entityQuery('node')
        ->condition('uid', $account->id())
        ->execute();
      node_mass_update($nodes, ['status' => 0], NULL, TRUE);
      break;

    case 'user_cancel_reassign':
      // Anonymize nodes (current revisions).
      module_load_include('inc', 'node', 'node.admin');
      $nodes = \Drupal::entityQuery('node')
        ->condition('uid', $account->id())
        ->execute();
      node_mass_update($nodes, ['uid' => 0], NULL, TRUE);
      // Anonymize old revisions.
      \Drupal::database()->update('node_field_revision')
        ->fields(['uid' => 0])
        ->condition('uid', $account->id())
        ->execute();
      break;
  }
}