How to turn off Cortana on a Windows 10 computer, so it doesn't take up power and can't hear or respond to your voice

You can turn off Cortana in Windows 10 through the Settings menu by taking away its ability to hear and respond to your voice.
Seattle Times

Can Cortana and Xbox be deleted from Windows 10, and how can buffering be eliminated from TVs connected to the internet?

Q: I use Windows 10 and have half a dozen items I would like to delete like Xbox, gaming and games, and Cortana. These either have an uninstall button that is not active or I am referred to “programs” ...
ExtremeTech

Cortana can't be disabled in the Windows 10 Anniversary Update

Microsoft won't let you disable Cortana in future versions of Windows. Post-Anniversary Update, Cortana and desktop search will be functionally identical. Share on Facebook (opens in a new window) ...