I tested, you can change emoji but not remove them

Personally never had this problem so far here. But I know it from other places. I just tried it here. I also do not see how to unreact or even to change my reaction emoji.

When I asked this a couple months ago, Rimu said that the only way was to choose another emoji: https://piefed.social/post/2012245

looks like there still isn't a way to remove it.

Good question. You can remove the accompanying upvote, but the emoji still stays.

Just don’t use emojis. They’re for children.