It would appear when you delete a save, it doesn't delete the map (which is cool if you want to restart on a previously played map) but there doesn't appear to be any sort of delete map button (unless I missed it, in which case it should probably be more obvious.) Having tried a couple different random maps means I've got a couple of folders with ~400mb of map files that I have no use for. Obviously I can delete them directly, but it seems like there should be some way within the game to delete them, particularly for less computer savvy people who wouldn't be able to easily locate and delete the files.