
Hi @DFlash,
Removing an activity in Activity section means that remove a notification, there is no way to remove a notification in Microsoft Flow currently.
Besides, the activities of the flow are not supported for archiving currently. If you would like this feature to be added in Microsoft Flow, please vote the following idea:
https://powerusers.microsoft.com/t5/Flow-Ideas/Clear-Notifications/idi-p/5402
Bets regards,
Kris