Hibernate Session.delete() an object if exists

In JavaDoc of Session class the description of delete method is:

Remove a persistent instance from the datastore. The argument may be an instance associated with the receiving Session or a transient instance with an identifier associated with existing persistent state.

My questions are:

1. I want to delete a detach object, can I use this method, AFAIK session first makes an object persistent from detach and then perform its operation. Am I right?
2. If I am not sure about the existence of the object in database, should I use Session.get() to check the whether or not it is null and then perform delete operation or I can use directly delete operation?

Here is a code snippet:

public void removeUnallocatedUserIfExits(final long itemId) {
    getHibernateTemplate().execute(new HibernateCallback() {

        public Object doInHibernate(Session session) throws HibernateException, SQLException {
            session.flush();
            session.setCacheMode(CacheMode.IGNORE);
            UnallocatedUser unallocatedUser;
            if ((unallocatedUser = (UnallocatedUser) session.get(UnallocatedUser.class, itemId)) != null) {
                session.delete(unallocatedUser);
            }
            session.flush();
            return null;
        }
    });
}

Is the okay?