the outer flared knob (what you pull on) simply screws onto the shaft; you'll want to unscrew this. next, you'll want to get a pair of fine-point (needle-nose) pliers to unscrew the other piece, kind of a grommet of sorts that fits into the hole in the back pad and screws into the firewall somewhere. the back pad won't come off unless you unscrew this piece also. you'll see what i mean when you get that first knob off, there are two holes in that piece for the tips of the pliers. careful with the plastic, tho.
i think this is right. if not, i'm a newbie and don't know anything.