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windows 10 after window 11 installed

Marcia Mucci 0 Reputation points
2026-05-08T22:52:29.1233333+00:00

Hi, I have run out of space in my C drive. Looking into it I found windows 10 still present. Can I delete Windows 10 safely without damaging Windows 11? And how do I go about it? Thank you for your assistance. It has created a problem with me reinstalling Ancestry because of space. I have tried to put as much as possible on D drive.

Marcoa

Windows for home | Windows 11 | Files, folders, and storage

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  1. Ivan B 114.6K Reputation points Independent Advisor
    2026-05-08T23:35:38.97+00:00

    Hi,

    If you've already performed the Disk Cleanup procedure to clean the windows.old folder from Q&A, after the procedure you can access the folder and delete it.

    Remember, if you've done the procedure, it's not possible to revert to the previous version of Windows 10.

    https://apps.microsoft.com/detail/xp9m26rsclnt88?hl=pt-BR&gl=TW

    A good option to check your files would be to download TreeSize, which is free, to analyze your C drive and see the large folders and files you're not using.

    Remember, don't delete anything without being sure. If you use TreeSize, if you have any doubts, let me know here and I can help you.

    If drives D and C are on the same SSD or HDD, you could take free space from D and put it on C to increase the available space, and I can instruct you on how to do that.

    If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".

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    Thanks

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  2. AI answer

    2026-05-08T22:52:40.4833333+00:00

    Windows 10 files left after upgrading to Windows 11 are typically stored in the Windows.old folder on the system drive. This folder allows going back to the previous version for a limited time. After that period, it is safe to remove it to free up space, but once removed, going back to Windows 10 using that folder is no longer possible.

    To remove old Windows installation files safely in Windows 11/10, use the built-in cleanup tools instead of deleting folders manually:

    1. Open Disk Cleanup:
      • In the search box on the taskbar, type disk cleanup, then select it from the results.
    2. Select the C: drive and select OK.
    3. Select Clean up system files, choose C: again, and select OK.
    4. After it recalculates, look for items such as Previous Windows installation(s) or similar large system items (these are part of Windows.old) and select their check boxes.
    5. Select OK, then Delete files to start cleanup.

    Disk Cleanup is designed to safely remove previous Windows installation files and other temporary/system files without damaging the current Windows 11 installation. Note that if it has been fewer than 10 days since the upgrade, deleting the previous version means the option to roll back to Windows 10 is lost.

    If disk space is still low after cleanup, also consider:

    • Moving new personal files to another drive:
      • Go to Start > Settings > System > Storage > Advanced storage settings > Where new content is saved, then choose D: (or another drive) for documents, apps (where supported), and other content types.
    • Turning on OneDrive Files On-Demand so that only placeholders are stored locally while full files remain in the cloud.

    If low disk space continues to block app installs or updates even after these steps, a reset or reinstall of Windows might be needed to fully reclaim space.

    References:

    AI-generated content may be incorrect. Read our transparency notes for more information.

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