Hello niels45,
This article gives you more information about managing the Apple email addresses used to sign into third party sites: Manage the apps that you use with Sign in with Apple - Apple Support. Follow this guidance:
"Manage your Sign in with Apple settings
In your Apple ID account settings, you see a list of apps that you use with Sign in with Apple. To view the information that you originally shared with an app, select any app in the list. You can also view a link to the app's Privacy Policy or Terms & Conditions.
If you chose to hide your email address from an app, you can turn off email forwarding to your personal email address to stop emails sent by a particular developer from reaching your personal inbox. You can also change your forwarding address to any email address that you have on file in your Apple ID account, or choose to stop using Sign in with Apple with an app or website.
If you use a Managed Apple ID at school or in the workplace, contact your system administrator to manage the apps that you use with Sign in with Apple at Work & School.
Turn off email forwarding
- On your iPhone, go to Settings, then tap your name.
- Tap Password & Security > Apps Using Apple ID.
- Select the app or developer, then tap Manage Settings.
- Select the app or developer, then tap to turn off Forward To.
Change your forwarding address
- On your iPhone, go to Settings, then tap your name.
- Tap Name, Phone Numbers, Email, then tap Forward to under Hide My Email.
- Choose the address that you want emails to forward to.
When you choose the email address, this applies to email from all apps and developers using Hide My Email.
Stop using Sign in with Apple with an app
- On your iPhone, go to Settings, then tap your name.
- Tap Password & Security > Apps Using Apple ID.
- Select the app or developer, then tap Stop Using Apple ID.
What happens if you stop using Sign in with Apple with an app
When you stop using your Apple ID with an app, you're signed out of the app on your device. The next time you visit the app or its associated website, you can either select Sign in with Apple to sign in again, or create a new account.
If you choose to use Sign in with Apple again, you're signed in to the same account that you previously used. Some apps might let you create a new password for your existing account so you can sign in again without using your Apple ID.
If you delete your account in an app where you use Sign in with Apple, you might receive an email from Apple that the app has revoked your Sign in with Apple account. If you want to create a new account with that app, you have to share your name and email address with the app again or create a new account using Sign in with Apple.
If you stop using Sign in with Apple with a developer of multiple apps
Some developers might use Sign in with Apple to give you an account for more than one app. If that's the case and you turn off email forwarding or stop using your Apple ID for one app, it applies to all apps from that developer."
We hope this helps. Let us know if we can assist with anything else at all. Take care.
