I think neemo meant AU=Anniversary Update. This folder gives you the ability to
"rollback" your computer to a point in time just prior to the udpate's installation. This is important as the AU update (there are now 7 different builds of version v1607) starting on Aug. 2nd has really only been pushed out the last 3 weeks to consumer's computers in any numbers. They are causing many many W10 systems to crash and burn. This "rollback" feature is reminiscent of the built-in windows System Restore utility available on windows systems since XP. It might be worth mentioning, that if you are installing it on multiple computers that are different brands such as Dell & HP, it might be best to wait a week or so and make sure all your loaded applications are working
BEFORE deleting the windows.old directory as neemo suggests. This way if you have a computer or two that gives you headaches such as loss of wifi network connectivity or loss of audio and reinstalling drivers doesn't fix it, you have a way to get back to a previous working version of W10 that was working such as v1511.
Another thing you can do if you have external hard drives available would be to use a solid W10 Image Backup program such as the free
Macrium, Acronis, or EASETodo software programs and image each of these computers once you've
"'stabilized them" and make sure they are working properly. Once you have these backup images in place on external media (you could also use a network server or Cloud backup), you could then go around to each computer and delete the windows.old directories, one computer at a time. Should one of them misbehave, or decide to just stop booting, or crash, or freeze, or hang and it's not easily repairable, you can just re-image that computer to an earlier version you have stored via your Image Backup program on external media in a matter of a few hours!
We do this a lot here those of us who are W10 Insider Testers; we voluntarily help Microsoft test new versions of W10. This might be a method that could help you.
Best of luck,
<<<BIGBEARJEDI>>>