First off, Scott's answer below is flat out wrong. Maybe in NH he's on point, but not here in TX. You can transfer ownership (the Deed) to the new owner, but your bank still has the primary lien on the property.
As an investor, I do this all the time. There are 2 ways you can go about it, you can "rent-to-own", or owner finance with a "wraparound mortgage".
You "rent-to-own" by putting the property under contract for a specific price to close 6-12 months out, with earnest money as their "down payment" that is non refundable and goes directly to you. You attach a lease to the contract as an addendum that has to be fulfilled. Keep renewing the contract/lease until they can get their own financing. Least amount of paperwork, least amount of hassle.
The "wraparound mortgage" is a document that will include your existing mortgage, and "wrap" the buyers mortgage around it (the one you write). Same downpayment that goes to you, and there are more tax reporting and servicing issues you need to consider (who's going to service the note, file interest deductions, etc) so this is more paperwork and more of a hassle, not to mention you need an attorney to draft these for you. Mark Torok or West & West in SA can do these for a fee. Yes, you do have "due on sale" issues, but the risk is non-existent unless you're really trying to defraud the bank or try to screw the bank over.
Let me know if I can assist.