You shouldn't have to amend the original note. All you need to do is have the note cancelled and/or get a release from the lender. If a deed of trust was recorded that secures the note, you might want to record the requet for full reconveyance. That should do it.
You don't need to amend the loan agreement. You just need a release and return of the original promissory note. if the loan was secured by a recorded deed of trust, you will need to record a deed of reconveyance.