How do I remove a pee stain (and smell) from a couch?

Our neighbors just bought a new couch and offered the old one to us last night. My SO went over there to take a look at it, and because the wife has advanced alzheimers, I told him to make sure she hasn’t had an ‘accident” on it. ( I guess I should have inspected it myself.)

Well, he just called me after getting it to our house and said that it has a “stain”, and it reeks!! I told him not to bring it into the house until I figure out if there is some way to clean it. Now I have a pee stained couch that reeks of old people on my patio!

Does anyone know what I can do to remedy this situation, or should I just have him take the couch to the dumpster?