You can reinstall Windows 10 from the cloud soon
Once this feature gets polished, you won't need to have a local copy of Windows 10 to reinstall it. The latest Windows 10 Insider Preview Build Fast Ring version has a "download Windows" option available when you want to reset your PC. Similar to what Macs can do for years, this feature will let you use your broadband connection to get a fresh install from the cloud. There won't be a need for a backup partition or thumb drive to reset your machine. The caveat is that it'll wipe your existing apps as well as your data if you choose to "remove everything."
This feature will prove handy when your version of Windows isn't working as it should. But you must remember that right now this is still a pre-release software version. You might want to wait until the final version is released before you attempt to reinstall Windows from the cloud.
Source: Engadget