Just draw up an agreement that the lease is terminated by mutual consent, that they are the only tenants living in it, that they are returning the property to you and giving up all claim to it, and that they have given you the keys and have received their security deposit back in full. 

They state that they can't do anything without the owners consent (which would be the bank, right)?

years, without the written consent of Landlord.Suggestions/ Comments welcome.

My leases always had a provision requiring my prior written consent of any guest that stayed longer than 7 days.I'm with Tevis - serve a cure or quit notice.

You'll need the owner's consent to do anything, but I've seen deals fall through due to fixable cracks and an afternoon and $50 might take care of it. :)

Even if he verbally says to give it to this person or that person, you still want this consent in writing.

I can't speak for the agent's side of things, but on the lending side when it comes to consumers/homebuyers:Several years ago I got consent from a bunch of past clients to use them as references. 

‣Buyer may assign or otherwise transfer any of Buyer’s rights, title, and interest in and to this Purchase Agreement to a third party without the Seller’s consent.

In order for it to pass, it would require a 2/3 consent of the neighborhood.

They may sell or lease their interest without consent of other joint owners.