How to revoke Sign in with Apple credentials for a specific app?
You can do this from the iPhone Settings. Open the Settings app then tap on your name at the top. Then press "Password & Security", then "Apple ID logins". They should all be listed there and can be deleted.
If you have the JWT id token, you should be able to decode it and retrieve the user info (name / email) from that directly.
For example, you can visit a site like https://jwt.ms/ and paste the id token there to see user-related data.
Edit: After doing some testing, it looks like the first/last name of the user is not in the decoded JWT token subsequent login requests. But, the email field is there, even though it is null in the apple id credential.
We have found a manual way to achieve this which has helped tremendously with testing so I thought it would be good to share here:
Go to https://appleid.apple.com and sign in
Scroll to down Security > APPS & WEBSITES USING APPLE ID > Manage
Click the appropriate app > Stop Using Apple ID
And then after clicking on the right app:
