Set<EOEntity> oldEntities = myEntities;
Set<EOEntity> newEntities = new HashSet<EOEntity>();
newEntities.addAll(myEntities);
newEntities.remove(_entity);
myEntities = newEntities;
_modelEvents.addEvent(new EOEntityDeletedEvent(_entity));
firePropertyChange(EOModel.ENTITIES, oldEntities, myEntities);
_entity._setModel(null);
}