Yes, I think there is some confusion here. You don't remove any bolt, you remove the nut off the shaft, (after carefully removing the cover or cap over the bolt, best down with it wrapped in a cloth and large vice-grips, so as to not damage the varnish over bronze coating which keeps it shiny), then the wheel is a mild taper fit, with a bronze wedge piece that fits in the groove designed for it to relocate the wheel in the same spot so you don't lose top dead centre, so make sure you don't lose that when you remove the wheel. It will best to get it off with a puller as others mentioned, the most elegant way, or, as I found, it is possible by being persistent with the wedged edges of a large screwdriver head tapped down between the back of the wheel and the bulkhead face mount, to ease it off, or, as Sunchaser found, (as I did with the upper helm), it might just come free with a tug, but that's unlikely. Of course, as others mentioned, once off you will be under extreme pressure to smarten it up, but a good sand down and re-varnish is quite easy, just a bit fiddly, but well worth the effort, and of course you can take it home to do this. I found a nice newly re-varnished wheel did wonders for the look of the helm.