Well, it's possible, but it's a bad idea. Until she refinances in her name only, you remain liable for the entire mortgage and will have to pay off the debt if she defaults. If you sign over your interest in the house before she refinances, you are left with a large debt and no ownership interest! You also remain liable for taxes and any special assessments for future anexation/development on the property. Also, until the mortgage is paid, it exists on your credit as a liability that may prevent you from getting a mortgage on your next house.
If you want to sell her the house without refinancing, go see a real estate attorney to draw up a "sale by owner" contract that protects your interests. Make sure the attorney addresses your interests, her interests, tax issues, whether you get to live in the house (co-owners can live in a house without permission from the other owners), what happens if she decides to sell later, if the market drops, the house burns down, etc. Expect to spend about $2k on attorney fees.
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This is not legal advice and you are not my client. Double check everything with your own attorney and your state's laws.
