One of my junior was observing users in our server and asked me why GUEST account is there in every database even though we have not created it. This is simple question but I really appreciated his observation.
GUEST account has been inherited from MODEL database. If you don’t want to create it in any database you create from scratch, you can delete that user from MODEL database and you have to manually delete that user from any database which has already been created.
One thing we can do is, rather than removing GUEST user, we can revoke its rights to connect.
REVOKE CONNECT FROM GUEST
Reference: Ritesh Shah