Greasy Fork is available in English.
Youtube Bulk Favs Remover - Have you ever wondered to remove all your favourite videos but you weren't able to find a solution? Yt-favs-remover is a script that helps to remove all your favourited videos from your favs playlist by simply clicking a button. Enjoy!
I believe this script no longer works. I wish it would be repaired, in addition to providing the same nuking option for Watch Later videos.