I have a busted lower steering neck bearing. What is the trick to remove the bearing race off the stem?

Two ways. The proper way is to use a bearing puller. The improper is to brake it and pemove it. If You have a place to get the tool- not a problem. If You don't- try with a hammer and a chisel or a nice sharp screw driver with a strong handle, If it doesn't work , You can use a grinder and cut thru the race carefully so Yoou don't dammage the stem too much.After that  Take it out in pieces. You don't care about the old race, because You are replacing it.
The trick is to put the new bearing race without damaging anything.
To install the stem race, put the tripple tree in plastic bag and put it in the freezer for about an hour . Find a 1,5' long metal pipe that has an inner ID slightly bigger than the stem. Put the new race on a hot plate to get hot. Use a thick leather glove. Now the new race should just drop in it's place, but if You are slow You will have to use the pipe like a driver. Just gently tap the race down  and You are done.
To install the race in the frame, put this race in the freezer for an hr and it will go very easy.