You can enter the “remove” edit yourself if you like.
Normally we discourage removing data as per our Data Removal Policy, but unreleased music is such a dangerous grey area that I believe we should err on the side of caution and not allow it. Many others have disagreed with this; we discussed it a while back in previous threads:
I think it is interesting information for a music database, whether it was released or not.
I would however disambiguate and annotate it, the way it’s curently presented (as a legitimate release) is definitely wrong. I wish we had a new ‘cancelled’ type or something that hides it from the official release discography which is not correct, but I guess MB’s not perfect yet.