User Configuration > Administrative Templates > Microsoft Outlook 2016 > Outlook Options > Preferences > Calendar Options > Schedule View
User
HKCU\software\policies\microsoft\office\16.0\outlook\options\wunderbar
This policy setting prevents Other Department Calendar from appearing in the navigation pane. If you enable this policy setting, Other Department Calendar will not appear in the navigation pane. If you disable or do not configure this policy setting, Other Department Calendar will appear in the navigation pane.