$obj->delete( ) 

Deletes the specified item from the repository, and from any relationships it belongs to. The delete() function does not remove any objects that had a “contains” type of relationship with the object being deleted. For example, calling delete() on a Router instance would remove that instance from the repository and remove that instance from any relationships that it was part of. However, the delete() function would not remove the Card objects to which the Router instance shares a “ComposedOf” relationship.

Consider using the remove() operation, if one exists, instead for a more complete action. For example, calling remove() on a Router will cause the Card objects it is composed of to be removed (which in turn could cause the Ports/Interfaces to be removed, and so on).