How to remove wheel mounting flange? JD 68 RER

Hey everyone! I've apparently got a key or more that has slipped on my old JD 68 RER. I'd like to get it back in action, but I don't know the proper way to remove the wheel mounting flange from the right rear wheel so that I can remove the chaincase cover entirely to work on the area. Do you know? Please help!

Thanks for your time!

JEff