I didn't see the second pic. That looks like it was peened on so the gear is probably on a flanged axle that would not come off unless you removed the axle from the bracket.

You might be able to get it off by using a hammer and a punch to try and narrow the side in the second pic so it will fit through the hole. Then have to peen it back on later. Or you could grind/file off the end sticking out in the second picture, but would likely have to replace that axle pin afterwards.