As per your description, the Privacy settings removed from the Office UI, here's how you can check its settings and disable it.
1.Open an Office app, e.g. Excel
2.Click File, then select the Options.
3.From the Options window, click Trust Center
4.Click Trust Center Settings
5.The next window should select Privacy Options
6.Click Privacy Settings
7.Uncheck the box for "Turn ON optional connected experiences"
8.Click Ok
9.Reboot, check if the notification still pops up.
attached is the registry key to disabled it if above mentioned does not work
Here is official article for your reference: Privacy-related changes to the Office UI