The action of deleting your subscribed
YouTube videos in which you have
no interest, and only leaving
the ones you actually want to watch.
The clean-out is a repeating action, which means you will find yourself deleting subscribed videos from the same subscription only by the subscribed account.
John keeps deleting
Ted's videos from his subscription box, he does his YouTube Clean-Out regularly
Mike's subscription box was so full of videos, he had
no choice but to do a full YouTube Clean-Out!