Persistence.createEntityManagerFactory("test", props));
EntityManagerImpl em = (EntityManagerImpl)emf.createEntityManager();
em.getTransaction().begin();
em.createQuery("Delete from TblGrandChild").executeUpdate();
em.createQuery("Delete from TblChild").executeUpdate();
em.createQuery("Delete from TblParent").executeUpdate();
em.getTransaction().commit();
em.close();