Nate, even without power, the SBC reservoir is pressurized to more than 2K PSI. You need to relieve that pressure, if you're going to be safe. And of course, build it back up before moving the car, once it is back together. Although I suspect that the SBC controller will notice if it has no pressure and would default to mechanical mode (front brakes only, no assist).

Anyway, good riddance to that system.