Assuming you're changing over from ball bearings to tapered. Here's how I removed the race.
1. Gather tools, Skinny pick or screw driver, hammer, small board, cats paw or cold chisel or drift.
2. Use pick or screw driver to get under and stretch rubber washer over race.
3. Almost a 1/4" space left between triple tree and race to angle punch. I used a cats paw, because that's what I had handy.
4. Put upside down, rest top of stem on board to keep it from getting damaged. Give a few taps with hammer to punch, working around race to loosen it, and then it should just slide off.
Some pictures: