ThemeController.php

public function deleteFromDatatableAction($id) {
        $em = $this->getDoctrine()->getManager();
        $entity = $em->getRepository('NomDuBundle:NomEntite')->find($id);

        if (!$entity) {
            throw $this->createNotFoundException('Unable to find Entity.');
        }

        $em->remove($entity);
        $em->flush();

        return $this->redirect($this->generateUrl('index'));
    }