Unfortunately there is no fancy interface for removing programs from the Open With menu like there is for adding items. To do this you’ll need to fire up the Registry Editor by opening the Run command (Windows Key + R), and then typing regedit into the box. Messing with the Registry Editor is not for the faint of heart, and I recommend that you understand how it works before diving into it.
The programs listed in the Open With menu should be located in one of two locations in the Registry:
HKEY_CURRENT_USER \ Software \ Microsoft \ Windows \ CurrentVersion \ Explorer \ FileExts \ .FileExtension \ OpenWithList
HKEY_CLASSES_ROOT \ .FileExtension \ OpenWithList
Note: Replace “.FileExtension” with the extension of the file for which you’re looking to modify the Open With menu.