If all you're trying to do is restrict access to the store, why not enable
Sideloaded Mode instead? You'll lose access to the home screen, but it'll hide almost all the links that require online access or an account to access. In your Kobo eReader.conf file, add the following to the ApplicationPreferences section:
Code:
[ApplicationPreferences]
SideloadedMode=true
If you need access to the store again later, apparently it's easy to switch back by setting that option to
false.
Edit: Although if you're trying to hide access to Settings to prevent the kid from doing a factory reset, that may not work.