I suggested disconnecting the F (field) wire because it can be "hot" with the generator/alternator output voltage. If the other end is not connected to anything and is well taped, it won't matter. But on general principles, I'd keep it unpowered. I would also disconnect the E terminal, so it is no longer connected to the chassis. If you don't, the cutout and regulator relays will still be powered. Probably won't hurt anything, but they still will suck up current unnecessarily.
Or, just gut the innards of the regulator, so nothing inside is connected to any of the terminals.