SOLUTION: Cannot Uninstall Microsoft Security Essentials from Windows 10

Recently, I encountered two different workstations that had upgraded to Windows 10 from Windows 7 on which Microsoft Security Essentials inexplicably was not uninstalled during the upgrade process by Windows Setup.  This is baffling, because MSSE isn’t designed to work with Windows 10 (it doesn’t work), and plus, it precludes the use of Windows Defender, which is essentially the Windows 10 upgraded equivalent of MSSE.

If you’re in the same situation, you’ll also discover that it is impossible to remove Microsoft Security Essentials from Programs and Features; when attempting to do so, you simply receive a generic message which states “You don’t need to install Microsoft Security Essentials.”  That’s great, Microsoft, because we don’t want to install it, we want to uninstall it.

Anyway, the solution to this problem is actually quite simple:

  1. Press Windows Key + R to open the Run dialog.
  2. In the Open: field, type:
    • explorer “%PROGRAMFILES%\Microsoft Security Client\”
      and press ENTER.
  3. Highlight the file Setup.exe, right-click it, and choose Properties.
  4. Choose Compatibility.
  5. Click Change settings for all users.
  6. Check the box next to Run this program in compatibility mode for: and choose Windows 7 from the drop-down box.
  7. Click OK on all dialogue boxes to exit all windows.
  8. In the search box at the bottom of the screen, type cmd. At the top of the pop-up window, underneath the heading Best matchright-click Command Prompt and choose Run as administrator.
  9. In the Command Prompt window that opens, type the following command:
    • “%PROGRAMFILES%\Microsoft Security Client\setup.exe” /x /disableoslimit
  10. Follow the instructions to uninstall.

That’s it!

Special thanks to corrado_boy_g60 at the Microsoft Community for information leading to this solution.