White vinegar always did the trick for me. Anything that can be tossed in the washer, wash first on cold with a generous amount of white vinegar, then wash with ordinary laundry soap. Spray undiluted vinegar on anything that can't be washed to a saturation point. If you have an carpet cleaning machine with an upholstery attachment just use vinegar with it. Allow to sit, but not dry. Blot to remove vinegar, or suck dry with carpet cleaning machine. The vinegar smell will dissipate. or you can repeat the process with plain water after you've finished with the vinegar approach. Although having washed it with commercial cleaner first may have 'set' the odour, so you might have to give it a couple of efforts with the vinegar. If you used diluted vinegar, just make sure the water is cold, warm water will set the urine smell.

As a cat lover, I must say this: please provide your room mate's cat with a second litter pan outside of his bedroom. Not being able to access the litter pan is extremely stressful to kitties, and most cats really do need more than one litter pan anyway to be happy.