How do I remove the Finder context option after removing an app?
Check in ~/Library/Services/. It probably installed a service there that didn't get uninstalled. You can safely delete the file.

If you don't find anything there, look in System Preferences → Keyboard → Keyboard Shortcuts → Services for an entry with the same name as the context menu item. Right-click that entry and it will offer you a Show in Finder option, from which you can delete the file.