Context Menu Manager is a small, free and portable program to help manage your Windows right-click menus.
The interface is cluttered, with an animated ad in the middle of the toolbar, assorted icons and buttons dotted around, and a status bar with some inaccurate system information (it gave us an "up time" that was several hours out, and a "Power" of 255% - whatever that means on a desktop).
There's also plenty of functionality, though. We chose ".docx" in the "File Association Manager" module and saw the file type, name, caption, icon, and the full context menu, each entry with its caption, name and command. Just about everything can be edited, replaced, or removed entirely, and there are some useful general options as well (clicking "Find Appropriate Program" opens a web page showing programs which can handle that file type).
A Context Menu Cleaner will find and remove invalid context menu options.
You also get a range of options to customise your right-click menus with useful extras: to start an application with high priority, to register/ unregister a DLL, to silently merge a REG file, to open any file with Notepad, to create a list based on the contents of folders, and more.
Context Menu Manager is a powerful tool, but it's not always intuitive, and there doesn't seem to be any documentation to answer the questions you're going to have - even if you're a Windows expert. It's still usable, if only as a system tweaker, but be careful, make regular system restore points/ backups just in case something goes wrong.