Have them confirm that anything left behind is trash and can be disposed of. 

Just as children should not eat lead paint (I'm not sure how you bite a wall) they should not ingest asbestos siding or "pop corn" either None, of this information is compliant with any current cities asbestos disposal laws.

Although then you are looking at demolition and disposal fees and permits probably, in addition to the new permit(s) for the new ADU.  

How much disposable cash do you have?

I just had one bolt mid lease leaving huge amounts of garbage I have no way to dispose of.

They are not interested in using equity at all as they already have disposable income/cash to invest.

If your STR has a septic and a garbage disposal, take out the disposal.  

The sellers don't have title to the property to dispose of it, but they still have responsibility for the loan.

Investments can be disposed of using 1031’s. 

Whether you're acquiring, disposing, or looking for a way to structure a creative win-win, I'm always open to collaborating on deals.I bring strong analytical support, accurate MAO calculations, and real market comps using tools like PropStream, Privy, DealMachine, and more.