You can't remove SugarCube v2.21.0 from Twine v2.2.1 because it's built into it, though it may be hidden by newer versions. You just need to upgrade.
Perhaps you missed my edit above, but as I mentioned there, "If you want to get rid of a story format so you can reload it, first go the the story format window from the main Twine page, then select any other story format, and now you can click the "trashcan" icon to remove that format." You may want to close and then re-open Twine after you remove a format.
If that doesn't work, try closing Twine, going to your "C:\Users\(your user name)\AppData\Local\Twine" directory and rename the "User Data" folder to something else. Then try opening Twine to see if that fixed your problems. If so, you can delete that renamed "User Data" folder.
Hope that helps! :-)