Custom services can be found in
If showing the service in the finder led you to the Applications folder it's a service that came bundled with an app. These should be defined in that app's
You can access it by right clicking on that application in the Finder, selecting
Show Package Contents and navigating to
Once you've opened the file look for the
Services key. Expanding it will show you all services that come bundled with that app. Deleting a service's key might remove its entry from
Keyboard > Shortcuts > Services. Be sure to make a backup of the .plist file first, in case something goes wrong and you want to roll back the changes.
Note that you might need extra software (like Xcode) to open