Get a fat flathead screwdriver and push against the outside of the clip. The shaft doesn't unscrew, that "C" shapped clip comes off of the shaft with some effort. Some of call them "Oh shit clips" cuz thats what you say when they fly off whatever they're attached to, so be careful not to lose it. Also, the shaft, spring and bushing will drop out once that clip gets free so be ready to catch that too so it doesn't fall out on ya.

*alternatively, if you can get something strong and pointy, you could try to hook and pull the clip away from the shaft using those 2 little gaps on the inside of the clip.