How does one change the owner of a folder in Rise 360?

Well, a couple of months later the question came up again, but with a twist. My finance dept messed up the annual renewal, so our access expired. Now that it's been reactivated and I've added myself to one of the seats. One of my team is no longer with the company, and there are tons of content he still owns. I can't remove him from his seat because he's already removed (we all were removed when access expired). I can't add him to one of the seats because he's literally not around. How do I change the ownership of his content in this case?