What do I need to sign over land deed and be free of mortgage?
We cannot give legal advice. The following is not a substitute for the advice of a local attorney. But we hope the information will be useful.
Your obligation to the builder will be defined by the contract you signed with them. Barring some sort of fraud, mistake or unconscionability in the contract (all of which are possibilities you should have a local attorney review), you presumably owe them money (since you defaulted) and they will be looking for any legal means to recover that money. However, you may have options available such as bankruptcy, in which you MAY OR MAY NOT be able to protect certain of your assets such as the land in question.
Of course they don't want you to get a lawyer involved, because then you are at their mercy. We advise you in the STRONGEST POSSIBLE TERMS to contact a local attorney to personally meet with you and review your agreement with the builder, counsel you as to the validity of the contract and what you appear to owe them, and counsel you on alternatives to paying the debt, including the benefits and detriments of declaring bankruptcy in your situation.