How do you remove a reaction made to a conversation or comment?

You can make up to 5 reactions on any conversation or comment. If you want to remove your reaction(s), click the "React" icon and scrolling all the way to the right of the react menu. You will see a [Clear Reactions] button, and clicking this will remove all of your reactions.

You can also click [Options] on the right side of the conversation or comment, and in that menu you will see the option to remove your reactions.