How to clean up the residual system file

after win7/win8 upgrade win10 Many win10 systems used in many user computers, most of them are upgraded by win7 system or win8 system, directly upgrade win10 under win7/8 system is not only easy to operate, And no technical support is required, so many users choose to upgrade directly, but many users find that the system disk file occupies a lot after upgrading win10. This problem occurs because after the user upgrades the win10 system, the files in the original system will remain in the system. In the disk, and provide users with services to restore the original system, if you do not want to restore to the original system after upgrading win10, then we can delete the problem, on the contrary, if you want to restore to the original win7/8 system, then you must keep these questions. Let's take a look at how to clean up the files stored in the original system!
Operation method
1. Open "this computer", right click on the "C drive", pop up the menu, select "Properties", click "Disk" clean up "

2," disk cleanup "dialog box, click on the" Clean up system files "

3, select the" previous windows installation "and" temporary windows installation file, "and click OK

4, click "Yes" to confirm the deletion, after deletion can not be restored to its original win7 /win8 system of

we will be able to remain original win7 /8 operating system by the above method The file has been completely removed, but our win10 system will not be able to roll back to the pre-upgrade system, please use this tutorial as appropriate!