Isn't there attic space above the office? If so I would try to trace the wires first. Also think about what the switch could power; an outlet, fireplace ignitor, attic vent fan, or even a remote switch for an HVAC unit are all examples I've seen. The worst one I've had was controlling an outdoor light that also had a hidden photoelectric switch. It was impossible to diagnose during the daytime.
Search all possibilities before cutting and capping those wires.
Search all possibilities before cutting and capping those wires.