How do you get out of a mortgage?

Sell the house.

You need to pay off the original mortgage. Ways to do that include:
1. Sell the house and use the proceeds to pay off the loan.
2. Refinance without your name on the new loan - for example, if you are currently a co-signer on a mortgage with someone else, have that person refinance without you as a co-signer.
3. If you have the assets - simply pay the loan off out of your pocket.