Worked at vet office, anything like urine or feces must be rinsed off thoroughly or it will smell. Obviously soap is needed too. Enough water and soap will get rid of it, although other cleaners incl enzymatic ones will work faster. No matter what, all that cleaner and soap has to be fully rinsed or it’ll still smell.

He should powerwash it outside or at a carwash. Or, if in an apartment he could rinse it for a while in the shower.