It's been a long time since I've dismantled one, but if you want to separate the cockpit from the ring in which it rotates, I don't think it can be done without breaking the two halves of the cockpit apart.
I once had a B-Wing that was near mint, apart from some deep scratches to the underside of the cockpit. I ended up removing the cockpit assembly (with ring) from the body and exchanged it for one from a donor vehicle.