Removing Custom Schema Extension in PRD

I know that removing custom schema extension in production level isn't supported out of the box:
https://support.oneidentity.com/technical-documents/identity-manager/8.1.3/configuration-guide/89#TOPIC-1250792

Now I like to get rid of one of this columns and I wondering why it isn't supported. The risk could be quite high, but is it worth to keep the garbage forever?

I could force it, if I change the ProductionLevel temporary to a non production level. Is there any reason, why I shouldn't do that?

Patrick

PS: We are on 8.1.3