3 methods come to mind. In the end of the steering rod stud there is a hole for a torx bit to counter hold. Insert torx bit and use a wrench on the nut. Beg, borrow, steal or rent an impact wrench. Use a prybar to put downward pressure on the rod, which forces it tighter into the hole, and unscrew the nut. My impact does the trick most of the time. Sometimes I have to pry or use counterhold method.