Getting her off the title won't get her off the mortgage, but I don't suppose it is your job to inform her of that.
You don't get her off the title, she does it. She does this by preparing some sort of deed and deeding her interest to you. Such deeds can be found in the LEGAL FORMS section of this web site and divorce lawyers typically perform this as part of their job as well. It might be in your best interest to have YOUR lawyer draft the deed to make sure your resulting title is in the best shape.
The term by the way is "QUIT CLAIM". That would be one avenue, but not in YOUR best interest. I'd prefer some sort of general or special warranty deed.