User Configuration > Administrative Templates > Microsoft Office 2016 > Global Options > Customize
User
HKCU\software\policies\microsoft\office\16.0\common\toolbars
This policy setting controls whether Office 2016 applications load any custom user interface (UI) code included with a document or template. Office 2016 allows developers to extend the UI with customization code that is included in a document or template. If you enable this policy setting, Office 2016 applications cannot load any UI customization code included with documents and templates. If you disable or do not configure this policy setting, Office 2016 applications load any UI customization code included with a document or template when opening it.