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());
    }

}