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Is it safe to delete Windows.old? When to wait and how to do it

By the Brightfix team. Updated October 7, 2026. Applies to Windows 11 (all versions) and Windows 10, Home and Pro.

Quick answer

Yes, it is safe to delete Windows.old once you are happy with the upgrade. It holds your previous Windows, so deleting it removes the option to go back. Windows removes it on its own after 10 days.

Before you start

  • Use the PC for a few days after an upgrade before you delete Windows.old. Once it is gone, you cannot go back.
  • If any personal files seem missing since the upgrade, look in C:\Windows.old\Users first and copy them out.
  • Delete it with Settings or Disk Cleanup, not by dragging it to the Recycle Bin in File Explorer.

1Check whether you still need Windows.old

Windows.old is your undo button for an upgrade, so check if you might still use it before removing it.

  1. Open Settings > System > Recovery.
  2. Look for Go back. If the button is there and active, Windows.old is still your way back.
  3. Think about the last few days. If apps, printers and games all work, you probably will not need to go back.
  4. Open Settings > System > Storage > Temporary files and wait for the list to load.
  5. Find Previous Windows installation(s) (some versions say Previous version of Windows) and note the size next to it.
What you should see

You know whether Go back is still offered and how much space Windows.old takes.

If it did not work: If Previous Windows installation(s) is not in the list, there is no Windows.old to remove, or Windows has already removed it.

Undo: Nothing to undo. This only looks.

2Delete Windows.old in Settings

This is Microsoft's own way to remove it, and it handles the special permissions on the folder.

  1. Open Settings > System > Storage.
  2. Select Temporary files.
  3. Clear every checkbox you do not want removed, especially Downloads and Recycle Bin.
  4. Tick Previous Windows installation(s).
  5. Select Remove files and confirm.
What you should see

The Previous Windows installation(s) entry disappears and free space goes up by about the size you noted.

If it did not work: Restart the PC and try again, or use Disk Cleanup in the next step.

Undo: This cannot be undone. After it is removed, Go back in Recovery no longer works.

3Or delete it with Disk Cleanup

Disk Cleanup does the same job and is useful if the Settings page will not load.

  1. Press Start, type Disk Cleanup, and open it.
  2. Choose drive C: and select OK.
  3. Select Clean up system files and choose C: again if asked.
  4. Tick Previous Windows installation(s). Leave other boxes as they are unless you know what they hold.
  5. Select OK, then Delete Files, and confirm the warning.
What you should see

Disk Cleanup runs for a few minutes and closes. The C:\Windows.old folder is gone.

If it did not work: If a small Windows.old folder is left behind, restart and run Disk Cleanup once more.

Undo: This cannot be undone. After it is removed, Go back in Recovery no longer works.

4Need more time to decide? Extend the go-back window

If you are not sure about the upgrade yet, Windows lets you keep the way back for up to 60 days instead of 10.

  1. Press Start, type cmd, right-click Command Prompt, and choose Run as administrator.
  2. Type DISM /Online /Get-OSUninstallWindow and press Enter to see how many days you have.
  3. To set 30 days, type DISM /Online /Set-OSUninstallWindow /Value:30 and press Enter. Any value from 2 to 60 works.
  4. Close the window.
What you should see

DISM reports that the operation completed, and Get-OSUninstallWindow shows the new number of days.

If it did not work: If DISM says the command is not supported, the go-back window has already closed or there is no previous Windows to return to.

Undo: Run the Set command again with /Value:10 to return to the default.

Upgrade typeCreates a large Windows.old?How to go back
Windows 10 to Windows 11YesSettings > System > Recovery > Go back, within 10 days
Full in-place upgrade (Installation Assistant or ISO)YesSettings > System > Recovery > Go back, within 10 days
Windows 11 24H2 to 25H2, or 24H2/25H2 to 26H2, through Windows UpdateUsually not. These use a small enablement package.Uninstall the feature update from Settings > Windows Update > Update history

Why this happens

When Windows installs a full new version over the old one, Windows Setup moves the old system files into a folder called Windows.old on drive C. Recovery uses it for the Go back option. Microsoft sets a 10-day window by default, and after that Windows deletes the old version on its own. The folder is often many gigabytes because it holds a whole previous copy of Windows. Smaller upgrades, such as 24H2 to 25H2 or 26H2, use an enablement package that turns on features already on the PC, so they usually do not need a full copy. The folder has protected system permissions, which is why File Explorer struggles to delete it.

Still stuck?

Why can I not delete Windows.old in File Explorer?

The folder holds old system files owned by Windows, not by your account, so File Explorer often shows access denied or stops partway. Forcing it by taking ownership can leave a broken half-deleted folder. The Temporary files page in Settings and Disk Cleanup are built to remove it cleanly.

Will deleting Windows.old delete my personal files?

No. Your current files live in your user folders, not in Windows.old. The only exception is after a reinstall that kept an old copy, where some old personal files may sit in C:\Windows.old\Users. Look there and copy anything you need before deleting.

How big is Windows.old usually?

It depends on the PC and the old Windows version, but it is often many gigabytes because it is a full previous copy of Windows. Settings shows the exact size next to Previous Windows installation(s) on the Temporary files page, so you know what you will get back.

What happens if I wait 10 days?

Windows removes the previous version by itself after the go-back window ends, which is 10 days by default. You do not have to do anything. After that, the Go back option in Recovery disappears and the space is freed.

Can I get Windows.old back after deleting it?

No. Deleting it cannot be undone, and Go back stops working. If you later want the old version, you would need to reinstall it from Microsoft's installation media, which means backing up your files and reinstalling your apps.

Related guides

How we checked this guide

Steps checked against Microsoft Support and Microsoft Learn documentation on October 7, 2026. Not yet tested by us on a freshly upgraded PC. Screenshots coming soon.

Changes

  • October 7, 2026: First published.

Sources

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