I would say that from your last picture,you need to remove the collar at the far end of the screw from the vice handle. It's probably held in with a split pin, or some other pin (plain, tapered or roll), but it should punch out; just be careful which way you knock it, if it's a taper pin.
You should then be able to remove the screw, and the nut should withdraw downwards.
The sliding jaw should then slide out.
Edited By peak4 on 27/06/2017 09:07:20