Hi
You still have to get the jamb nut off the inside befor you can turn fitting that goes thru the frame.Once you have that off then you can pull the assembly thru the frame and get it apart.The bulkhead fittlng that goes thru the frame also will not turn in the frame because of a stop incorporated in the way the fitting fits in the frame,some times its six sided like a nut or they have a little slot
Good luck Thomas