Guide · Windows 11 and 10

How to delete the Windows.old folder safely

After a Windows feature update or upgrade, a folder called Windows.old appears on C: and quietly takes 10 to 30 GB. Here is what it is for, when you can remove it, and how to remove it properly.

Updated 22 September 2026 · 3 min read

What is Windows.old?

C:\Windows.old is a copy of your previous Windows installation. Windows keeps it so you can roll back from Settings > System > Recovery > Go back if the new version gives you trouble. The rollback window is 10 days by default, after which Windows cleans the folder up on its own.

Is it safe to delete?

Yes, once you are happy with the update. Deleting it does not affect your current Windows, your apps or your files. The only thing you lose is the ability to go back to the previous version.

Check first: if you upgraded from an older PC setup and your files did not come across, look in C:\Windows.old\Users\<your name> before deleting. Copy anything you still need.

Method 1: Settings (Windows 11 and 10)

1. Open Settings > System > Storage.
2. Click Temporary files and wait for the scan.
3. Tick Previous Windows installation(s) and untick anything you want to keep, such as Downloads.
4. Click Remove files.

Method 2: Disk Cleanup

1. Press Win+R, type cleanmgr and press Enter.
2. Pick C: and click Clean up system files.
3. Tick Previous Windows installation(s) and click OK, then Delete Files.

Why can't I just delete it in Explorer?

The folder is owned by the system and contains files only TrustedInstaller may change, so Explorer asks for permissions it will not grant. Taking ownership and forcing it through works but is slow and can leave a half-deleted folder. The two methods above use Windows' own cleanup handler, which removes it completely.

Want to keep the option to go back for longer?

In an administrator terminal, DISM /Online /Set-OSUninstallWindow /Value:60 extends the rollback window to 60 days (the maximum). Run it before the current window closes.

How Cosmo Cleaner handles it

AutoBeast, part of Cosmo Cleaner, measures the previous installation (walking it with hard-link dedupe so the figure is real) and, if you tick it, removes it with Disk Cleanup's own Previous Installations handler after creating a fresh restore point. Because it cannot be undone, it always waits for your explicit tick and is never part of a scheduled run.

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