User Configuration > Administrative Templates > Microsoft Outlook 2016 > Disable Items in User Interface > Predefined
User
HKCU\software\policies\microsoft\office\16.0\outlook\options
This policy setting allows you to hide the Quick Steps Gallery in the Ribbon. By default, the Quick Steps Gallery is included in the Home tab of the Outlook explorer Ribbon. If you enable this policy setting, you will hide the Quick Steps Gallery in the Ribbon. If you disable or do not configure this policy setting, the Quick Steps Gallery will be included in the Home tab of the Outlook explorer Ribbon.