Not going to happen, practically. To delete them, it'd have to download them and reupload them. At that point you might as well just do it yourself.

I personally use the comment field as something to sort on for my soup playlists. Singles have an "s", albums have an "a", humor and "h" and so on. Then jemplode can make my Artist/album, Artist/single, and humor/artist playlists automatically.

Matthew