Update net names and net groups in an existing design

Hi Cadence,

I need to rename some nets in my design and they are part of netgroups I created previously. However it seems renaming netgroup instance name is not that easy, since there is no rename button can be used. When I tried to create new net groups and remove the old ones, I got the error ORCAP-1828:

I am pretty sure that this netgroup has been removed from my hierarchical design, but I can still find it in the design cache, Netgroup Definitions, cleanup cache didn't work.

Any comments helpful will be appreciated, my goal is to keep the previous PCB design, I just want to update the net names.

Thanks!