User Configuration > Administrative Templates > Microsoft Outlook 2016 > Outlook Social Connector
User
HKCU\software\policies\microsoft\office\outlook\socialconnector
This policy setting prevents users from connecting Office to social networks (including SharePoint), and prevents Office from displaying contacts and feeds from their social networks. If you enable this policy setting, users cannot connect Office to social networks. If you disable or you do not configure this policy setting, users can connect Office to social networks.