Bulk delete walks

I used sync now because it looked like today’s run wasn’t picked up, but unfortunately that also synced all my walks, that I previously deleted. I can delete only one at a time because of the 1-hour limit. Is there a way to do bulk delete, or to schedule them for deletion? I don’t mind waiting, but it is a bit annoying to have to remember each hour to delete another walk. Alternatively, is there a way to block walks from syncing, or to mark a deleted activity as “should not be synced again”?