Who's is it anyway?

Hopefully your purchase contract delineated what items would be theirs, and what would be yours.
Barring the agreement wasn't reduced to writing, prepare to litigate the matter.
Or, be smart and let them take the junk they want.
If you go that route, make sure its agreed to in writing and that after they "pick and choose", it's over!

 

They should not enter the building without your permission. If they want the items they would need to go through the court. Somewhere in your purchase documents it should indicate the contents of the building were part of the sale, but even if not, after 3 years they don't have much of a claim to make.