class DeleteForm

class DeleteForm extends ConfirmFormBase {

  /**
   * The taxonomy term being deleted.
   *
   * @var \Drupal\taxonomy\TermInterface
   */
  protected $taxonomyTerm;

  /**
   * {@inheritdoc}
   */
  public function getFormId() {
    return 'forum_confirm_delete';
  }

  /**
   * {@inheritdoc}
   */
  public function getQuestion() {
    return $this
      ->t('Are you sure you want to delete the forum %label?', [
      '%label' => $this->taxonomyTerm
        ->label(),
    ]);
  }

  /**
   * {@inheritdoc}
   */
  public function getCancelUrl() {
    return new Url('forum.overview');
  }

  /**
   * {@inheritdoc}
   */
  public function getConfirmText() {
    return $this
      ->t('Delete');
  }

  /**
   * {@inheritdoc}
   */
  public function buildForm(array $form, FormStateInterface $form_state, TermInterface $taxonomy_term = NULL) {
    $this->taxonomyTerm = $taxonomy_term;
    return parent::buildForm($form, $form_state);
  }

  /**
   * {@inheritdoc}
   */
  public function submitForm(array &$form, FormStateInterface $form_state) {
    $this->taxonomyTerm
      ->delete();
    $this
      ->messenger()
      ->addStatus($this
      ->t('The forum %label and all sub-forums have been deleted.', [
      '%label' => $this->taxonomyTerm
        ->label(),
    ]));
    $this
      ->logger('forum')
      ->notice('forum: deleted %label and all its sub-forums.', [
      '%label' => $this->taxonomyTerm
        ->label(),
    ]);
    $form_state
      ->setRedirectUrl($this
      ->getCancelUrl());
  }

}