Unhook the positive battery cable, first, and unbolt the cable from the starter. Now, remove the two bolts from the rear of the starter. If the starter still won't come out, unbolt the starter gear cover (4 bolts) on the left side of the engine and remove the reduction gear and it should pull out then.
Most 4-wheeler problems are caused by a loose nut connecting the handlebars and the seat!!
You only need two tools in life -- WD-40 and duct tape. If it doesn't move and should, use the WD-40. If it shouldn't move and does, use the duct tape.