Anyone who is not baptized cannot be disfellowshipped or disassociate themselves. They just go back to the world. If they are unbaptized publishers, they are no longer unbaptized publishers, and are looked at as worldly people. If they fade, the study conductor will likely hound them to death at this stage.
Baptized people, on the other hand, can be disfellowshipped if they leave on the grounds of the mishandling of pedophile cases. It is called apostasy. But such ones can just start missing meetings and not going out in service, or move and not leave a forwarding address. Such ones would become inactive. The catch is that once you are inactive, they are going to start hounding you to come back. They call this reactivation. At that point, if you still have apostate viewpoints or are doing things that you could get disfellowshipped for, they can and will do so.