How to delete windows.old in Win10?

How to delete windows.old in Win10? Now win10 is just a preview version, and there is no official version yet, but I believe that some of my friends are like Xiaobian, like early adopters, and have used win10. Some people install it directly through win7, win8 or 8.1. This operation is easy to install, but the system will display a few G or even 10 G backup files in the C drive in order to back up the original system files or information. .old. So how to delete the windows.old file after the win10 system upgrade? In fact, the method is very simple, the system automatic function can be cleaned up.
Open “My Computer”Go into the hard drive and find the C drive (the small system here is installed on the C drive, I believe most people are the same as Xiaobian, but some people are not installed on other disks)
Right click on the right mouse button "C drive" “—— In the pop-up menu, select “Properties"

The following icon will appear, directly select “Disk Cleanup” , the system will scan, please wait patiently for a few minutes

When the scan is completed, the following interface will appear, directly select “clean system files” will also scan the system, please wait a few minutes later

After the scan is completed, in the pop-up window, find "Previous windows installation", put this item in front of √, then make sure to clean up.

This step may take longer, depending on the size of the backup file, the time will be different, wait patiently again.

After the prompt is completed, enter the C drive, you will find that the WINDOWS.OLD file is gone, or become 0KB size.