Is there a safe way to remove genres?

[skeptic]

When setting up MAME I missed a step.  When I put my mame rom zips in the games directory it automatically created a new genre "No Matching Rom for ROM: <romname>.zip" for each and every rom, over 1000.  Needless to say, I want to clean up all that junk so I don't have to sort through it when setting genres for movies and such.

How can I safely clean up all these invalid genres?  If it's as simple as going in mysql admin and removing them I can, but I don't want to mess the database up.

[Marie.O]

Did you try going into Media Browser, and rename that Genre in there?

rgds
Oliver

[skeptic]

I can see the genre, and look at it's properties, but I see no way to delete it.

edit:  if it matters, I do not have any roms for those genres any longer.  well, maybe a few, but I'll change those roms to have a proper genre first.

edit2:  Just noticed you said rename, not remove.  Not sure what that would accomplish.  After fixing the issue that cause this, I correctly re-added the roms which created a list of valid genres.