delete user in SQL SERVER database : Hi I am executing this code to create user in my database.

    CREATE LOGIN john WITH PASSWORD = 'john123';
    GO
    
    USE mytestdb;
    GO
    CREATE USER [john] FOR LOGIN [john]
    GO
    ALTER USER [john] WITH DEFAULT_SCHEMA=[dbo]
    GO
    ALTER ROLE [db_datareader] ADD MEMBER [john]
    GO
    ALTER ROLE [db_datawriter] ADD MEMBER [john]
    GO
    GRANT EXECUTE ON SCHEMA::[dbo] TO [john]
    GO


but I want to delete this my created user. how can I delete this.


Thank you in advance.