Unable to delete domains

[JoshWhite]

I have an issue with unused domains in my file geodatabase.  I have partially implemented the Local Government Information Model so it added a number of new domains.  Now I have some old domains that I would really like to remove to avoid any confusion.  I have come up with a list of about 8 domains that I would like to remove.  Trouble is that I always get an error message:

Failed to delete a domain from the database.
The domain is used as a default domain.

I cannot gaurantee that I don't still have a default set somewhere but I don't think I do.  I can't understand what I need to do to remove this "lock" so that I can clean things up.  It seems that this is just a waste of space and possible performance killer.

[jkarmon]

I'm encountering the same thing.  I'm calling them "phantom domains".  I've run python scripts to check for orphaned domains and after each of these domains I cannot delete, there is a whitespace in the list.  I've also noticed that when assigning domains to a field, I have a series of blank spaces before the domain list contents show (the exact same number of blank spaces of domains I cannot delete from my database).  Anyone else encounter this?

PS -  orphaned domain script:

         Finding Orphaned Domains in a Geodatabase 

         script to check which fields in feature classes in workspace have domains applied:

          arcpy - Listing feature classes with active domains? - Geographic Information Systems Stack Exchange