If you are both on the Deed, then you both own the property. There should be a document stating what percentage that goes with the deed.
Big question is what is your goal? Do you want out of the ownership? Rates are very good for refi right now.
YES, your friend can refinance - unless you have a signed legal agreement that prevents your friend from doing so.
The mortgage loan was signed by your friend. Whatever private arrangement you had with your friend is between you and your friend.
It seems that you own the property without the obligation to pay the mortgage loan.
Frankly, I am more concerned about your friend.
Hopefully, you have prepared and signed a thorough agreement before you purchased the property that clearly defines your and your friend's rights and obligations.
Both of you should contact a knowledgeable real estate attorney.
You might find this blog helpful: