I have about 1500 installed... and Air is now slowing to a crawl. I could do a full reinstall, but then I'd have to play the campaign again to get double down back (not that I ever really use it...)... or I can delete them one.... by.... one.... is there a batch way of doing it? :)
If all you want to do is remove the custom maps... they are in C:/users/<<username>>/AppData/Roaming/CreeperWorld/customgames
Back up that directory and empty it out, and all the custom maps will should be removed.