"This contract is assignable with written consent from seller."

also, the cable and phone company won't drill holes in your property until they talk to you or you write a letter with expressed consent ( at least, that has been my experience in richmond).

Below is the consent agreement on their application.  

Perhaps a provision on a lease should read" No AHJ are allowed to enter the premises without Owner's written consent" The number only work with that possible non conforming unit rented as an Owner occupied.    

You might "assume" payments under a contract but you will never assume a mortgage without the lender's/note holder's consent.

if you finance it, you should be careful if you demolish the house without the lenders consent as the lender may be considering that house as part of the collateralThen again, part of your strategy should include to salvage the house so that you only need to build one additional house.

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. 

@White KandlezIf you have don't have ownership rights on the property, I am not sure if you can have the property listed on MLS through realtor for sale without the consent of the owner on records.

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

MOST IMPORTANT:  Have your attorney prepare proper disclaimers and informed consent documents to be signed by the seller and notarized.