Is there no way to clean up "All activity" area?

my “All activity” area is filled with commits from github.com/Automattic/wp-calypso , a repo which I used to watch, but I don’t anymore. how can I clear my “All activity” area?
I tried everything, even actively ignoring the repo, unsubscribing from all repos, unstaring everything, turned off “Automatically watch repositories&teams” and so on, and I still get all their commits in my “All activity”. why does this happen?