The key cap should be lifted from the top edge. You can use any "tool" that allows you to get under the top edge, and lift the edge away. Something flat and relatively thin will do (like a small flat-head screw driver). In this video I am using some tweezers.

Removing the key cap from the top edge should result in the 2-piece key armature remaining attached to the keyboard. This is the ideal situation, because it is easy to then replace the key cap once you blow out any dirt that was under the key.

If one or both parts of the armature detach along with the key cap, we'll address that below.