How to Remove a Program on the "Open With" Dialogue

To Remove a Program that Windows lists in the "Open with" dialogue:

Open Regedit

locate the registry key:

locate the file extension in question and delete the program you do not want associated. (example, if you do not want Notepad.exe in the list of programs in the "Open With" dialogue for TXT files, delete Notepad.exe from the .txt\OpenWithList key)

If the program you are looking for is not located in the HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\filetype\OpenWithList key, some items in the Recommended Programs and Open With lists appear as the result of values within the HKEY_CLASSES_ROOT\filetype key and its subkeys.