Detailing Symbol Styles

During testing I've created a new style and now wish to delete from the system.

I am also having a problem with the Cells being read from multiple files - there seems to be a never ending loop as to where these

symbol cells are being read from.

In the DetailingSymbolStyles.dgnlib the one I want to delete is greyed out as per attached

Where do I go to delete the unwanted style - this is a network company dataset