remove By ID

Query query = em
				.createQuery("SELECT p FROM Project p WHERE p.projectId = :id");
		query.setParameter("id", 2);
		Project project = (Project) query.getSingleResult();
		Collection<Employee> empl = project.getEmployeeses();
		for (Employee employee : empl) {
			Collection<Project> proj = employee.getProjectses();
			Iterator<Project> iter = proj.iterator();
			while (iter.hasNext()) {
				Project next = iter.next();
				if (next.getProjectId() == 2) {
					iter.remove();
				}
			}
		}
		em.remove(project);