Any Real Estate lawyers?

[Dan Alva]

Hello All. Can some give advice what to do in the below situation? 

My parent own a house which has my mothers/fathers and sisters name on it. My sister is moved out and married and my parents want her to sign off on her share of ownership. However she will not out of spite due to unrelated family issues. She never put any money into the house. Her name is on the deed because the bank needed another co signer and she had a job at the time so they accepted her. The house is paid off now.

How would my parents be able to get her off the deed if she is unwilling to sign off?

Appreciate any advice.