Unsubscribe from topics

In the User Control Panel, it's only possible to show all subscribed topics that have been updated in the last X days. Which is fine if you want to read old things, but useless if you easily want to unsubscribe from old things because you get to see from the most recent going backwards in time.

What's needed is a feature to display subscriptions that haven't been updated in X days or more. For example, you get displayed topics that haven't been updated in 90 days or more. It's useful to get rid of the old subscriptions, so that what's displayed is tidier.