Deejay, the first step, if there is any corrosion (which mainly means if the key is exposed to oxidation in the outside air, and isn't constantly wet with oil) is to soak it with penetrating oil. Then you need to break it loose, before removing it. These steps are the same as for a Woodruff key, but you break it loose in a different way: you apply a punch to the end of the key and tap it axially to slide it along the keyway. Often the objective is to get one end of the key to lift up in the keyway, so you can lever it out, but if the key is close to the end of the shaft, you may be able to just tap it and slide it off the end of the shaft. In practice you usually can't do this though, because there is a bearing behind the end of the key, right where you want to tap it from, so you are mainly trying to get it to rise up higher in the keyway. Then you can put something under it and lever it up and out.
If the key is right on the end of the shaft and the bearing is close to the key, you can use the bearing's inner ring as a pivot to lift the key. Instead of tapping the key along the keyway, you lower the free end of the punch and tap the end of the key upward. With one end of the key immovable against the inner ring of the bearing, it is usually easy to lift the key in this way. Of course you can use a tiny chisel to get underneath the free end of the key, but this requires lots of tiny chisels of different widths, and often scores the keyway, so it is a bit on the crude side.
