JPA Error (on delete) : java.lang.IllegalArgumentException: Removing a detached instance

This is a problem I got while deleting a record.

What I've figured is that you cannot delete a persistent object that you got very earlier (ex: as a result of a relationship of another object)

What's needed to be done is to refetch that object again by using find and delete it.

Solution:
EntityManager em=CWUtil.getEntityManager();
em.getTransaction().begin();
m=em.find(Membership.class, m.getId()); //<-Fetched again here
em.remove(m); //<-Deleted here
em.getTransaction().commit();
em.close();

Solves the problem!