How to I delete WINS name from Network > Advanced > WINS I'm unable to clear the NetBIOS and Workgroup names (when I try, the current NetBIOS name appears grayed out, and always returns, even after I press "Apply"). I've already issued the command

sudo launchctl unload -w /System/Library/LaunchDaemons/com.apple.netbiosd.plist

I don't have any file sharing enabled, nor is there an active directory configured.
Turns out that the solution was to 


Remove all the NetBIOS name entries in /Library/Preferences/SystemConfiguration/preferences.plist (there was one for every interface)
Killall -9 cfprefsd
Issue the 

sudo defaults delete/Library/Preferences/SystemConfiguration/com.apple.smb.server.plist

command for good measure.
Restart


I hope this can help others.