What is the Windows.old Folder and How Do You Delete It?

Upgraded from an old version of Windows? You have a Windows.old folder on your computer, and it’s using up a huge amount of space. You can delete it, but it’s different from deleting a normal folder.

The Windows.old folder isn’t something new with Windows 10. But, prior to Windows 10, you’d only see it if you purchased a new version of Windows, and then used it to upgrade a PC that came with an older version.

What Is the Windows.old Folder?

This folder is created when you upgrade from one version of Windows to another, starting with Windows Vista. The Windows.old folder contains all the files and data from your previous Windows installation. You can use it to restore your system to the old version of Windows if you don’t like the new version. If you’re looking for a specific file that wasn’t properly copied to your new Windows installation, you also could dig into the Windows.old folder and find it.

Essentially, the Windows.old folder just contains the old Windows system. From the Windows system files to your installed programs and each user account’s settings and files, it’s all here. The new version of Windows just keeps it around in case you’d like to go back to that older version of Windows or in case you need to dig in and find a file.

But, don’t wait too long—Windows will automatically delete the Windows.old folder to free up space after a month.

Downgrade to a Previous Version of Windows

It’s easy to downgrade from Windows 10 to Windows 7 or 8.1. After installing Windows 10, head to Settings > Update & Security > Recovery. You’ll see a “Get Started” button under “Go back to Windows 7” or “Go back to Windows 8.1”, depending on which version of Windows you had installed before you upgraded. Click this button and Windows will restore your old Windows operating system, using the Windows.old folder as the source.

Again, as the interface notes, this option is only available for a month after you upgrade. Windows will automatically remove the Windows.old folder to free up space after a month, so that’s how long you have to decide whether you want to stick with your new version of Windows.

Prior to Windows 10, it was also possible to do this. For example, here are Microsoft’s tedious instructions for using the Windows.old folder on a Windows 7 machine to restore an older Windows installation. With Windows 10, it’s now easy.

Recover Individual Files From the Windows.old Folder

If you need to recover individual files from your old Windows installation, you can recover them from the Windows.old folder. This should just be a matter of opening the File Explorer window, accessing the Windows.old folder at C:\Windows.old, and browsing your file system. Your personal files will be located under C:\Windows.old\Users\your_name.

How to Delete the Windows.old Folder to Free Up Space

The Windows.old folder can take up quite a bit of space. In a best case scenario, it might be 12 GB or so of hard disk space. But it could easily consume 20 GB or more, depending on how large your previous Windows installation was.

If you try to delete the Windows.old folder from File Explorer like you would any other folder, you’ll receive an error message. You could potentially bypass this error message by modifying the Windows.old folder’s permissions. However, you don’t need to bother with that.

To delete this folder the easy way, use the Windows Disk Cleanup tool. In Windows 10, click the Start button, search for “Disk cleanup,” and then launch the Disk Cleanup app. You can also right-click the C:\ drive in File Explorer, select Properties, and then click the “Disk Clean-up” button on the “General” tab.

Click the “Clean up system files” button. You’ll see an option for “Previous Windows installation(s)” appear in the list of things you can delete, and Disk Cleanup will tell you how much space those files are taking up. Select that option and use Disk Cleanup to wipe the previous Windows system files away. You can also use this tool to delete other unnecessary files taking up space on your system drive.

There’s no downside to removing the Windows.old directory. As long as you’re happy with your current Windows system and don’t want to downgrade—and as long as you’re sure you have all your important files and don’t need to grab a straggler from the Windows.old folder—you can go ahead and remove it. And remember, Windows will automatically remove the Windows.old folder a month after you upgrade, anyway.

Chris Hoffman is a technology writer and all-around computer geek. He's as at home using the Linux terminal as he is digging into the Windows registry. Connect with him on Google+.