User Configuration > Administrative Templates > Microsoft Outlook 2016 > Miscellaneous
User
HKCU\software\policies\microsoft\office\16.0\outlook\addins\equivalentcomaddin
This policy setting allows you to deactivate Outlook web add-ins if the associated COM or VSTO add-in is installed. If you enable this policy setting, users will not be able to use Outlook web add-ins where the corresponding COM or VSTO add-in is installed and you have provided the following information for each add-in. "Value name": Specify the Id of the Outlook web add-in, as noted in its manifest. Note: Do not add {} around the Id. "Value": Specify the programmatic ID (ProgID) for the Outlook COM or VSTO add-in. If you disable or don't configure this policy setting, users will continue to be able to use any versions of the add-in that are installed. For more information about when to use this setting, see https://go.microsoft.com/fwlink/p/?linkid=2156690