User Configuration > Administrative Templates > Microsoft Office 2016 > Tools | Options | General | Web Options...
User
HKCU\software\policies\microsoft\office\16.0\common\general
This policy setting controls whether users can download templates from Office.com from within the Office applications. If you enable this policy setting, users will not see featured templates from Office.com in File | New and on the Office Start screen and will not be able to download templates from within Office applications. If you disable or do not configure this policy setting, users will see featured templates from Office.com in File | New and on the Office Start screen and will be able to download templates from within Office applications. Note - Enabling this policy setting does not prevent users from downloading templates from Office.com using their Web browsers.