After upgrading windows 7 to windows 8 pro on our test machine we realized that windows 8 leaves previous version windows system files on the hard drive located in windows.old. Pressing simple delete will not remove it from the hard drive. To have it permanently removed one needs to run disk cleanup utility.
To remove windows.old from windows 8 follow the steps below.
Click on “computer” from the start menu.
Once computer window lunches. Right click your system partition (most of the time its local disk (C:)) Select properties.
In general tab click on “Disk Cleanup”
In Disk Cleanup for (C:) or other system partition. Click on “Clean up system files”
In “Files to delete:” Select “ Previous Windows installation(s) press ok