HOW TO DELETE THE WINDOWS.LD FOLDER FROM WINDOWS 10 AFTER UPGRADE
When you upgrade your computer to a new version of Windows 10, or you install a preview build, the installation process saves a copy of the previous version in the "Windows.old" folder.
This is part of the safety mechanism in case the upgrade process goes wrong. If the installation fails for any reason, the system can use the Windows.old folder to undo the changes. Also, if the upgrade completes successfully, the backup copy of the previous version will be kept to provide the option to rollback in the case the new installation is causing issues.
First things first: If you think you might want to downgrade from Windows 10 back to the previous version, don't delete this folder.
Second, unless you're seriously strapped for space on your hard drive, you don't have to do anything: Windows 10 will automatically delete the Windows.old folder one month after you performed your upgrade.
If you'd rather not wait -- if you want to reclaim that storage now -- you can delete the folder immediately, though not in the way you might expect. Indeed, if you simply click the folder and then press the Delete key, Windows will tell you you need permission.
In this Windows 10 guide, I will walk you through the steps that you can get rid of the Windows.old folder to free up several gigabytes of space to store more important files.
Here's the proper way to delete the Windows.old folder:
Step 1: Click in Windows' search field, type Cleanup, then click Disk Cleanup.
Step 2: Select Windows (C:)
Step 3: Click the "Clean up system files" button.
Step 4: Wait a bit while Windows scans for files, then scroll down the list until you see "Previous Windows installation(s)."
Step 5: Check the box next to the entry, then make sure there are no other boxes checked (unless you do indeed want to delete those items). Click OK to start the cleanup.
As you can see from my screenshots, Windows 8 was occupying nearly 25GB of space -- a full 10 percent of my solid-state drive. Needless to say, I was glad to be rid of it and get that space back.