Try to uninstall the app, or disable it? I noticed it popped up as a Play Store app which I had previously installed (ditched the AT&T stock ROM long ago): https://play.google.com/store/apps/d...er.toolbar.att
If rooted, just find the associated app, and uninstall or freeze with Titanium.
I agree the AT&T Browser Bar is awful. Takes up too much screen real estate (yeah, I know it often hidden, but still annoying as it pops up often) and has functions that are easily performed in other ways. Useless, as most of AT&T's bloat is.