This really isn't all that difficult.. +1 on the dremel. If you can get any kind of a cut off tool, get it..
Can't remember if there is a fastner or any kind of body clip on the rear of that nut, or if it threads into the Bay itself. This would be your first point of interest. If it's a fastner, cut the bolt. If it's a clip, cut the head from the bolt and remove the clip. If it threads into the bay, drill it out and tap it.
there is a clip type thing behind that, it swivels which explains why it wont come off...you will have to cut it off somehow, or take off the fender liner above that wheel and hold it while someone else ratchets it off...cut it off tho, it is easier