User Configuration > Administrative Templates > Microsoft Office 2016 > Collaboration Settings
User
HKCU\software\policies\microsoft\office\16.0\common\general
"Never ask user": Do not ask users if they want to send back changes to the author. | "Prompt for 'send for review"': Ask users if they want to send back changes to the author only if the document was sent using Send For Review and not with ad-hoc review. | "Always prompt": Ask users if they want to send back changes to the author for documents sent using either Send For Review or ad-hoc review.