Good luck, I had the same problem. I was having my front bumper replaced and getting new fog lights (one broke from a minor accident) and could not get it off either. I ended up taking it to the body guy and told him about it, and I believe he was able to get it off by taking off the front bumper. The bolt I had problems with seemed to keep spinning out when I put the socket on it, and there is absolutely no way to get a wrench on the back to hold it.
Ack. I don't want to pull the front bumper. I think I will leave the bracket on. Mainly, removing the fog light allows more cool air up into my CAI even with the bracket still on.
A lot of people believe by removing fog lamps or fog lamp hole covers they allow more cool air to be "forced" into their intake system. There really isn't any difference if the fog light is there or not. As long as their is air around it it will suck it up, and air coming through the fog lamp hole or underneath the car is about the same temperature anyways. If that is your only purpose, don't waste your time.