This article is for those Windows users who have recently upgraded to Windows 10 from Windows 8/7. After upgrading to Windows 10, Windows created a folder named windows.old on the PC where the old OS installation files are located. These files are saved on your system to give you the option to revert to the previous operating system. Now this opportunity is available to users for only 30 days. So if you've decided to stick with Windows 10, it's a better decision to delete that folder and reclaim around 18GB of free space.
How to delete windows.old installation folder in Windows 10
Step 1 - Research Disk Cleanup in the search box on the Windows 10 taskbar. Click Disk Cleanup from the search result.
Step 2 - Clicking on it will bring up the disk cleanup information window. This will show the drive that Windows is installed on. The blue flag shows the installation unit.
For a few seconds it will search for how much space it can recover.
3 pass - Now select the windows.old folder from the list which has the maximum size in GB.
Press ok and windows.old will be removed from your system.