How to Remove File Type Associations Using the Registry Editor

Associating a file type with a program can be done using several ways such as using the Open with… dialog and selecting the “Always use this app to open” checkbox, or via Default Programs or Default Apps. While you can set or change associations using GUI, there is no option provided to delete an existing file type association. This post tells you how to remove file type associations using the Registry Editor.

Remove a File Type Association Using the Registry Editor

Let’s say you’ve incorrectly associated a file type named .bak, and want to remove the association. Use these steps to remove the file association settings (for .bak) from the registry.

Before proceeding, create a System Restore Point. Additionally, export each registry key listed below to a .reg file prior to deleting, just in case you need them.
  1. Start the Registry Editor (regedit.exe), and go to this branch:
    HKEY_CLASSES_ROOT\.bak
  2. Note down the (default) value data in the right-pane. It’s the ProgID associated with that file type.
    find progid for a file type registry
  3. Right-click the key .bak, and choose Delete. Click Yes to confirm.
  4. Go to the following HKEY_CURRENT_USER keys and delete the .bak key.
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.bak
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\Roaming\OpenWith\FileExts\.bak

    This should remove the file association settings for .bak file type. The deleted file type should now be treated as unknown by Windows; which is exactly what we wanted.

    Delete the Progid as well (optional)

    If you also want to clean up ProgID key for that file type, which you noted (bak_auto_file) in Step #3 above, you must do so only if that ProgID bak_auto_file is not used by any other file type. This is important.

    How to find if any other file type(s) is mapped to the same ProgID?  Do a search (for Data containing the ProgID string – match whole string only) in the Registry Editor. Or run one of the commands given below to find it out.

    This time, let’s take the example of txtfile Progid. To view the list of file types that use the txtfile ProgID, run:

    Example: txtfile (progid used for .txt)

    assoc | findstr /i "txtfile"

    assoc findstr progid association

    (or)

    reg query hkcr /d /f "txtfile" /s

    reg query progid association

    In the above case, the following file extensions are still using the txtfile progid:

    .LOG | .SCP | .TXT | .WTX

    So, you should not remove the HKEY_CLASSES_ROOT\txtfile registry key, as it would break the association settings for file types that use this key.

    Now, let’s use the above method and find out if any other file extensions are using the bak_auto_file Progid. Running the command for bak_autofile, you get this:

    assoc findstr progid association

    As no other file types are using this ProgID, you can safely delete this key:

    HKEY_CLASSES_ROOT\bak_autofile

Summary

To remove the file association settings for .bak file type, we’ve deleted the following registry keys:



HKEY_CLASSES_ROOT\.bak
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.bak
HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\Roaming\OpenWith\FileExts\.bak
HKEY_CLASSES_ROOT\bak_auto_file

That’s it! Hope this guide helped you delete an unwanted or incorrect file type association on your Windows computer.


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About the author

Ramesh Srinivasan founded Winhelponline.com back in 2005. He is passionate about Microsoft technologies and he has been a Microsoft Most Valuable Professional (MVP) for 10 consecutive years from 2003 to 2012.

10 thoughts on “How to Remove File Type Associations Using the Registry Editor”

  1. This doesn’t seem to work anymore. I have a valid association in HKLM\Software\Classes and no association in HKCU\Software\Classes. When I remove the extension from HKCU\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts (it had UserChoice and Hash keys) and reboot, the association is still active and remaining in Default Apps. My HKCR association is ignored.

    • @Sid : Also try here: HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\Roaming\OpenWith\FileExts
      If not, upload the file asso report for that particular file type to Pastebin.com and post the link. You can use filetypediag to get the report.

  2. “bak file type was mapped to ProgID “txtfile”, ”

    Shouldn’t this be “txt file type was mapped to ProgID “txtfile”, “

    • @bob: I’ve removed the sentence and rephrased it for more clarity. Thanks for commenting. Appreciated!

  3. This worked great. Thanks!
    Clear explanations. Solid examples. I liked the inclusion of multiple methods.
    I shared on FB and twitter 🙂

  4. Thank you for the instructions. The following steps work for me.
    1. Delete HKEY_CLASSES_ROOT\.bak
    2. Delete
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\FileExts\.bak
    3. I don’t have the Roaming key, so skip this step.
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\Roaming\OpenWith\FileExts\.bak
    4. I change the path to the preferred application in HKEY_CLASSES_ROOT\bak_auto_file\open\command
    and
    HKEY_CLASSES_ROOT\bak_auto_file\edit\command
    5. Reboot and it’s working.

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