How to remove ignition cylinder to replace

Try an easier solution first. Slide two pieces of paper in the slot, one on each side of the broken part of the key, and a little past it. Mix up some epoxy, put a small dab on the end of the key handle or another thin piece of metal. Slide that in to glue it to the key. The paper will prevent the glue from sticking to the cylinder. Hold the handle in place with a wire or rubber band for a couple of hours, then pull it out. Don't get carried away with the glue. More is not better because it will squirt out on top and bottom and stick to the cylinder.