Do you mean the brake light is stuck on? If so check the front brake handle, mine stuck after I changed the grips. I had to adjust it down lower on the handle bar.
Or are you talking about the in line switch that leads to the back caliper. If that is froze you might need to loosen the exhaust to get enough room to get wrenches on it. I replaced mine on my 08 softail custom a little bit of a pain to get to.