PHPortal Ownership is based on the first row in the top user table with the id = 1. That user is the top owner and the only one with access to the control panel of that specific PHPortal instance.

At the same time other users can belong to the local access role of 'owner'. This would enable said user, if user had access permissions to the 'takeOwnership' method, to take ownership of a object and its subobjects from another user even another user in the same 'owner' role.

Again, even with all that said only the top level user, which cannot be deleted, can have access to the control panel of the management interace.