Is there an easy way to filter and review Marketo programs that are older than a year?

Not sure if there's an easy way to do this, but I do know that every 6 months, Marketo will go through and deactivate any triggered campaigns that haven't had any activity. You might be able to look for inactive programs, and then archive those as a start to clean-up.

You could use Campaign Inspector and filter to inactive triggered campaigns or by last modified date to get at that.

Do you know where to find the campaign inspector? I see that you need to go under admin, not sure where to enable after that...

To enable Campaign Inspector, go to Admin - Treasure Chest. Once enabled, go to Marketing Activities and you should see it up at the top by the campaign queue.