According to
http://www.ghacks.net/2016/07/26/you...ays-microsoft/
there is no longer an off switch for Cortana in the 1611 anniversary update.
Although you can still disable it via a registry entry those days might be numbered as well, since the update also limits what policies (and registry entries) can do on W10 Pro. http://www.ghacks.net/2016/07/28/mic...indows-10-pro/
Most notably you cannot disable the store anymore and neither can you disable Windows tips nor the their consumer experiences policy, which allows MS to push applications (think Candy Crush) to your PC.
Of course this list could be extended at any time.
Enterprise and Educational SKU are not affected.
Might be a good time to defer updates and think about an alternative OS....