Cannot delete app after connecting with App Script

I was trying oauth through Google app script (using the oauth2 library). I followed through on the 3LO tutorial here and it worked on the first try but subsequent logins just throws an error.

Since this is all just for testing anyway, I wanted to delete the app off the Developer dashboard but it’s giving me this error:
“We couldn’t delete this app, as it is currently installed somewhere. Uninstall it from all applications and try again.”
I’ve already disconnected to the service on the app script side - is there any other reason why I cannot delete the app?

Thanks.