code: private function createDeleteForm(Tag $tag)
      {
          return $this->createFormBuilder()
              ->setAction($this->generateUrl('blog_tag_delete', array('id' => $tag->getId())))
              ->setMethod('DELETE')
              ->getForm()
          ;
      }
docs: Creates a form to delete a Tag entity.
  
  @param Tag $tag The Tag entity
  
  @return \Symfony\Component\Form\Form The form