Removing Windows Movie Maker requires a workaround since Windows considers it an essential part of Windows. Here is the procedure to delete Windows Movie Maker completely from Windows.

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Restart
Windows XP in Safe Mode. To do this, start tapping on the F8 key as soon as your computer boots, before the Windows XP loading screen. In the menu that is then shown, select Safe Mode.
Once Safe Mode starts, Click on Start Menu, then go to Run and type "cmd". This will open up a command prompt where you will be entering a few commands:

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Type these commands one-by-one and you will completely remove Windows Movie Maker.
- del "c:\system32\dllcache\*wmm*.dll"
- del "c:\system32\dllcache\moviemk.exe"
- del "c:\Program Files\Movie Maker\*.*"
- rmdir /s "c:\Program Files\Movie Maker"
Make sure to include the double quotes around the path of the files, and replace c: with whichever drive Windows is installed on. Once done, just restart your computer. You should have successfully removed Windows Movie Maker from your Windows installation.