How to take away authorization to access a steam account from a website?

[Roger Doofenshmirtz]

My brother gave access to his steam account to some shoddy third party website. That website changed his steam account name, it's bio, and other stuff like it's profile pic, real name etc. He did not lose access to the account itself. How do I deauthorize that website so that it won't be able to access his account again?

[cSg|mc-Hotsauce]

Originally posted by Roger Doofenshmirtz:

My brother gave access to his steam account to some shoddy third party website. That website changed his steam account name, it's bio, and other stuff like it's profile pic, real name etc. He did not lose access to the account itself. How do I deauthorize that website so that it won't be able to access his account again?

His account is compromised. On his account, follow all the steps...

Scan for malware. https://www.malwarebytes.com/

Deauthorize all devices https://store.steampowered.com/twofactor/manage

Change your password on a secure device.

Generate new back up codes. https://store.steampowered.com/twofactor/manage

Revoke the api key https://steamcommunity.com/dev/apikey

[Zekiran]

Individual sites will keep your information forever.

The only way to prevent this, is to NOT USE THEM, EVER.