Can I delete the Windows.old folder? How to remove it safely
Yes, if your PC has been working fine since the last big update. Remove it with Settings → System → Storage → Temporary files → Previous Windows installation(s). Don't delete it in File Explorer.
When Windows installs a major update (like a new Windows 11 version) or you upgrade from Windows 10, it keeps your old system in C:\Windows.old. That's what lets you roll back if something goes wrong, and it's often 15–30 GB.
Is it safe to delete Windows.old?
Yes, as long as you're happy with the current version. Once it's gone you can't use Go back in Recovery settings. Windows deletes it by itself after about 10 days anyway, but you can do it sooner if you need the space now.
Before deleting, check that none of your personal files ended up only in Windows.old\Users. That's rare, but it happens after some upgrades.
The right way to delete it (Windows 11 and 10)
- Open Settings → System → Storage.
- Click Temporary files.
- Tick Previous Windows installation(s) and click Remove files.
On Windows 10 you can also use Disk Cleanup → Clean up system files → Previous Windows installation(s).
Why you can't just delete it in File Explorer
The folder is owned by the system, so Explorer will ask for permissions over and over and usually fail halfway, leaving a broken half-deleted folder. The Settings method removes it properly.