When you right-click on a file, one of the options you see is “Open With”. These usually contain what Windows thinks are valid programs to open particular file types. Now, sometimes, when you have bad installers or uninstallers, some programs leave their mark on this context menu. Basically, if you want to clean out this long list of junk that accumulates here, you have to edit the Registry.
Open the Registry Editor and navigate to HKEY_CURRENT_USERSoftwareMicrosoftWindowsCurrentVersionExplorerFileExts
Now, for example, if you have to remove programs from the Open With menu for AVI files, find the extension on the left that corresponds to AVI files and click on the “+” sign to expand it and find the “OpenWithList” key. In the right pane you should see a list of programs, such as “wmplayer.exe”, “notepad.exe”, “mspaint.exe”, etc. Select the ones you don’t want and delete them.
Next, navigate to HKEY_CLASSES_ROOT and find the same extension. Again, navigate to “OpenWithList” and delete the unwanted programs. This key is where Windows reads from when using the All Users profile. Now you will only see the programs that you want in the Open With list… well, most of the time; the problem is that Windows also reads the Open With list from another registry key: HKEY_CLASSES_ROOTSystemFileAssociations
Here’s where it reads the default Open With list from, but I strongly advise you against changing it because it might affect multiple file types.