iPad is not windows,
iOS is a (Apple say UNIX) *NIX / darwin / Machtel derivative....
You dont have to understand what means, but you do have to understand
that means no registry. If there are any extra files, you can delete them
by installing the App again, and then delete it and answer yes to deleting
files and settings, also say yes to removing it from gamecenter if you
get that question. If not, its as totally deleted as if you had deleted the
reg-keys in windows, and even more so.