Back in the main Storage menu, click 'Change how we free up space automatically,' and designate which parts of your drives you want to be cleaned up by Windows on a regular basis. If this whole deep dive into Windows 10's storage management tools has you interested in running a leaner system, you can use this opportunity to look into Storage Sense. That's it! Windows.old and anything else you wanted rid of are now deleted and you should have some extra storage space.