question- tear down a garage addition

[Annette A.]

We built a 3 bay garage like 7 years ago... taxes have since gone sky high. we owe only like $80G and the property is valued around $160G?.... we are thinking of selling but the market is not great in our area.  We could probably rent out the house for $850 as is. We have thought about tearing down the garage to rebuild on a pc of land we own outright, to gain more value.  Anybody know if there is any legal issue with tearing something down? as for mortgage company, aren't we only responsible for what is owed? (It wasn't built to any code specimen, we built it. It is off... and is probably unsafe. ... it is a BIG structure 3 bay, 2 story addition...  the garage doors were put on the eve side and is not sitting squarely on the slab, and the sill is starting to pull up on inside wall and lean out off the foundation.  It looks stable at this point but the question is, is there a legal issue with tearing it down?