I was asked a question today, on a second floor building that has been converted to 3 different offices, the filing system is where the old washer was (converted hall closet 90 y/o building). The pipes are still there and not going to be used.
The question was if it should be capped if not in use.
IMO, I think it should be to prevent sewer gases from getting in if the traps dry out, which it more than likely is. But before I gave any advice I thought I would throw it out there to you guys.