Unfortunately, it's changed a bit since Win7; the slider bar under Control Panel > User Accounts and Family Safety > User Accounts no longer
completely disables UAC, as you've seen. Here's what you can do to turn it all the way off:
- Go to the Control Panel and navigate to System and Security > Administrative Tools > Local Security Policy (assuming you use the "Category" view; it'll simply be under Administrative Tools > Local Security Policy if you have "View by icons" set).
- In the right pane, scroll down to the settings that start with "User Account Control". You can fully disable UAC, or tailor its behavior to your desires.
Very important caveat: Fully disabling UAC this way (via Local Security Policy, not the slider) completely prevents Metro apps from running! M$, in their *cough* "infinite" wisdom, decided Metro apps are not allowed to run this way; of course, that's the
only reason they won't run

. Of course, I wouldn't touch a Metro app with
someone else's 11-foot pole, even if I had Win8, so YMMV.