We bought a home and on my property there is an easement to the property behind me. The owners behind me bankrupted and left. Do I still have to allow an easement?

Yes... if it's a recorded easement you do.

It belongs to the owner of the adjoining property, whoever that may be.

Yes, it belongs to the property, not any specific owner, so unless you are going to buy the other property, and give it some other entrance, this is it.