For some reason we still allow removing labels by hand, even though they get auto-cleaned by ModBot when empty. What's more, this removal can happen even if the label has relationships, as long as it's not used as a release label.

While I can see why we'd keep the manual removal option for recordings as an exception (orphaned recordings that are completely lacking in data, can't be easily merged and need removing are not super uncommon, and removing all relationships can be a pain), it doesn't make sense to me at all to still allow manual removal of labels. Most bad labels just get used as a release label and become empty (auto-cleaned) as soon as the release is fixed. In the rare case a label with relationships really doesn't exist and should be removed, surely it's ok to remove the relationships and let ModBot clean it up just like we would for an artist in the same situation.