Deletando em @oneToMany

@Entity
@Table(name="teste1")
public class Teste1 implements Serializable {
	private static final long serialVersionUID = 1L;

	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	private int idteste1;

	private String nome;

	//bi-directional many-to-one association to Teste2
	@ManyToOne(fetch=FetchType.LAZY)
	@JoinColumn(name="teste2")
	private Teste2 teste2;
}

@Entity
@Table(name="teste2")
public class Teste2 implements Serializable {
	private static final long serialVersionUID = 1L;

	@Id
	@GeneratedValue(strategy=GenerationType.IDENTITY)
	private int idteste2;

	private String nome;

	//bi-directional many-to-one association to Teste1
	@OneToMany(mappedBy="teste2", orphanRemoval = true, cascade = CascadeType.ALL)
	private List<Teste1> teste1;
}

public class Teste {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		EntityManager entityManager = Persistence.createEntityManagerFactory("PERSIST_UNIT").createEntityManager();
		
		Teste2 teste2 = entityManager.find(Teste2.class, 1);
		
		entityManager.getTransaction().begin();
		entityManager.remove(teste2);
		entityManager.getTransaction().commit();
	}

}

Transaction tx = connection.beginTransaction();
		 connection.merge(obj);        
		 tx.commit();