I use the nozzles frequently, but the default library is garbage. I'm trying to delete it permanently because is takes up real estate. I've tried deleting all of teh individual nozzles in it, but when you get to the last one, it won't allow you to delete.
I have a suggestion...in the option menu (top right corner of the panel) you can choose Nozzle > Libraries and uncheck the libraries you don't want to see. This will allow you to hide "Painter Default" and Painter 11 nozzles" so you will only see your new custom library of nozzles.
In the future, this will save you from having to delete each nozzle one by one (just hide it all in one step)
Out of curiousity, what does your new nozzle library have in it? Would love to see it...