Cannot Detach reference from "Managed Model"

This is nonsense. Civil software should not interfere with my ability to do my drafting.

We have a project, with several people working on it. Apparently, someone got into my sheet files using InRoads (probably SS4) to do something, and now every one of my sheets is a "managed model". I am working in vanilla MicroStation SS4. I can attach references all I want, but I am not allowed to detach any of them. I get the "You cannot Detach a model from a managed model. The operation is cancelled" message.

I am not in Inroads. I just attached the file a few minutes earlier. but I'm still not allowed to detach it?? Because somewhere along the lines, someone with IR SS4 opened my file?

How can I strip all "design" information out of my sheets so that they can be drafted like any other sheet file without this "managed model" nonsense?
How do I UN-manage a model?

I know that I can start IR SS4 and detach the references in question. I shouldn't have to do that.
I shouldn't have to waste an InRoads license just to detach a couple of useless references.
Especially since the refs in question weren't even attached with InRoads!!

Please fix this so that the draftspeople of the world can get our jobs done.