AP StyleGuard is an automated style-checking tool for Microsoft Word or Outlook, developed by Tansa in collaboration with The Associated Press.

Yes, you can turn StyleGuard’s style-checking functionality on or off at any
time using the Enable/Disable button.

On Windows: You can turn off AP StyleGuard by clicking on the “Enable StyleGuard” button in the Word ribbon. This will remove the StyleGuard pane from the right side of your document and turn off style checking.

On the Mac: Same premise, but slightly different look. In
the StyleGuard pop-up app, look for the “stop” button when StyleGuard is enabled. Click to disable. This button will then become a “play” button icon; click to enable StyleGuard.

Also, on the Mac, you can just quit the StyleGuard app to turn it off since it does not appear inside Word.