I suggest you contact IBM Support. They are the only ones who can solve your problem.
I don't know whether the problem you are seeing is covered by APAR IY66383, which is open for nvmaputil not working correctly when unmanaging interfaces, or not. But that problem will be fixed in FP03, which is due out April 1. If there's a test fix for IY66383, you would obtain that from Support. If your problem isn't fixed by that, then they'll need to know about it, so that it can be fixed.
Level 3 Support for Tivoli NetView for UNIX and Windows
Tivoli Software / IBM Software Group