code: public function onSectionDelete($sectionId)
      {
          /** @var Articles_Entity_Table_Article $table */
          $table = ORM::getTable($this, 'Article');
          /** @var Articles_Entity_Article[] $articles */
          $articles = $table->findInSection($sectionId, null, 0, true);
          foreach ($articles as $article)
          {
              $table->delete($article);
          }
      }
docs: Удаляет статьи при удалении раздела сайта
  
  @param int $sectionId
  
  @since 3.01