Welcome to the Make community!
According to https://www.make.com/en/help/access-management/teams,
Members of a team have access only to scenarios and data that belong to their team.
Therefore, to prevent access to that team’s scenarios, the user must not be an organization owner or admin, and also not a member of the private team.
Hope this helps! Let me know if there are any further questions or issues.
— @samliew
P.S.: Did you know, the concepts of about 70% of questions asked on this forum are already covered in the Make Academy. Investing some effort into it will save you lots of time and frustration using Make later!