How to add a redirection at the end of Delete entity process?
Finally, this code works:

&lt;?php
namespace Drupal\sel\Form;
use Drupal\Core\Entity\ContentEntityDeleteForm;
use Drupal\Core\Form\FormStateInterface;

/**
 * Provides a form for deleting Service entities.
 *
 * @ingroup sel
 */

class ServiceDeleteForm extends ContentEntityDeleteForm {

  public function submitForm(array &amp;$form, FormStateInterface $form_state) {
    $entity = $this-&gt;getEntity();

    $entity-&gt;delete();
    $form_state-&gt;setRedirect('elsewhere', [some argument]);
    drupal_set_message($this-&gt;getDeletionMessage());

  }

  protected function getDeletionMessage() { some code }

  public function getQuestion() { some code }

}