The title of you thread is about disassembling a "cog". But your question is about disassembling a wheel. I don't mean to offend, but your confusion, not to mention your very nieve questions about wheel dissasembly, indicates to me that you lack the experience to rebuild your wheel safely. If you really want to disassemble your wheels and properly rebuild them you are going to need to spend even more money on a wheelbuilding book, tensiometer, truing stand, spoke prep, and spoke wrenches. Moreover, it would be wise to dig up and old wheel that you could use for practice. And its going to take some time, probably days, to read, practice, and rebuild your wheels. Don't attempt to rebuild your first set of wheels without the right equipment (especially a tensiometer). that would be like working in the dark, and you will end up with poorly built wheels. It simply isn't worth it if your only motivation is to change the color of your budget hubs. You are much better off just getting new wheels and selling your old ones...or better yet just ride what you have and stop nitpicking about how it looks. No one really cares...trust me.