Are you trying to remove the stem, or just the bearing race?
If you're removing the bearing race so you can put in new tapered roller bearings, you can cut off the old bearing race with a dremel - just be careful not to cut the steering stem. If you dont want to cut it off, you can usually pound them off - work your way around the bearing with a hammer and punch/chisel and it will slowly move. I'm not sure there is a non destructive way to remove those, as its too tight to get a bearing splitter in there.