@Bu18 You can read instructions on how to delete Stadia account from the article below, but I would advise please read carefully what the consequence is first before doing it
https://support.google.com/stadia/answer/9617647
What happens when you delete your Stadia account
When you delete your Stadia account:
- You'll permanently lose access to your games and all other purchases made in Stadia. Your games and other purchases cannot be downloaded or moved to another Google Account.
- Deleting Stadia from your account will immediately terminate any active Stadia subscriptions. You won't be refunded for any unused remainder of your subscription period.
- Your game progress and achievements will be permanently deleted.
- Your list of friends, chat history, and other activity within Stadia will be permanently deleted.
- Your full player name will be permanently deleted. You will not be able to use this name if you sign up for a new Stadia account.
- Your saved screenshots and clips will be permanently deleted.
- This will not delete your saved live stream videos, which will still be available in YouTube.
- This will not delete any data collected or stored by publishers of the games you’ve played.
- This will not delete any Google Assistant data.
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Stadia Guides are not employed by Google. Opinions are my own.