How to unmap domains with the plugin

I have a few multisite installations, but only one of them has domains mapped to it. I’m keeping a development copy of it for testing – the subsites are all mapped to domains using your domain mapping plugin.

I’d like to access the sites using folders (the original setup). I looked for instructions on changing back to just the folders set up, but the only link that seemed relevant was broken. What would I need to do to revert back without making a mess of the subsites?