You might be in the clear, but make sure you've traversed every menu and sub-menu in the BIOS configuration. One of my laptops -- I don't recall which, sorry -- has the settings located a few levels deep with some very unsuspecting terminology. Even when I was looking specifically for it (I knew it was in there!), it took me a few minutes to actually find it.

Also, WRT turning it off, there are typically two options: deactivate and disable. One is just "temporary" (in that it can be turned back on later), the other is (supposedly) permanent and "impossible" to revert. Make sure you choose the right one (for you).