Admin Option to Unsubscribe members from Individual Posts

Once a member is no longer active, how can I as the admin make sure they are not subscribed to any topics? Could we add a one-click button that unsubscribes members from all topics, including random posts they subscribed to?

I know there is a location where we can subscribe and unsubscribe to general topics, and when I check those, nothing is chosen, but I still have emails going out for those same members on individual posts they chose to be subscribed to.

I need a way to unsubscribe them to stop the emails on those posts from no longer going out any longer.