Hello and welcome to the forums @Challenges1
You can't remove them, but they do remove themselves in time.
If you have a challenge and are waiting for others to sync, just quit it and you can join another one.
Keep on stepping!
Best AnswerHow much time until they go away. Very annoying to see old challenges - too much clutter on screen. Once ended at least by the weekend they should be gone
Best AnswerHi @JEANSABLE usually a day or so. A winner has to be declared and then it goes in another day or so.
Best Answer