What bike do you have? If it's a G5 the fender doesn't move. It's a PITA to get the tire out. set the bike up on a thick board with the center stand so the wheel can fall down a ways, then you can turn it to get it out. Or you can lean the bike way over and prop it up with a stool or some such as it gets leaned over, and pull the wheel out from below and sideways. I took care of the problem by bobbing my rear fender and then it was pretty easy to get the wheel out. If you have a B5, or it is indeed an iron barrel, remove the bolts on the front end of the fender brace tubes on each side and the fender will rotate up from the rear. I think a C5 works that way, too, but not sure.
As far as removing the wheel goes, take out the cotter pin, remove the outer nut, stick a screwdriver in the other end of the axle and pull it out, watching for the spacers and remember where they go. Pull the wheel to the left which will disengage it from the rubber cush drive and it comes right out, after you figure out how to get it past the fender Take a couple of pictures before you disassemble it, so you absolutely remember how to get all the pieces back together!
Bare