Ask HN: Turning over a website to a nontechnical “client”

A few years ago I built a simple Joomla based website as a favor for a friend and agreed to host it gratis on my "project server". Since then he and I co-founded a start-up which failed and we are no longer on good terms. I am still stuck hosting his site, and removing the malware that gets installed every couple of months on his, now ancient, version Joomla.

I am currently in the process of changing hosting providers and have to do something with this site. Something in this case means either giving him his data and walking away or doing a migration to another platform and making him responsible for it. The challenges are: 1) He doesn't have the technical skills to keep it up to date or clean up the mess after a hack. 2) I'm not interested in being involved in the ongoing maintenance of the site.

What I'm looking for is any advice/best practices for doing this type of turn over.