Yes, you can delete the worlds from your GeneratedWorlds folder if you don't want to keep those. Default path is %appdata%\7DaysToDie\GeneratedWorlds\ . Even that isn't really necessary for 1.0 but it would keep your folder cleared of old stuff.
The main thing for 1.0 is to remove all mods from your Mods folder until you can get updated versions of them or verify that they still work correctly.