Restrict Access with Teams
Use Teams to restrict user access to an organization. Create teams, add users to those teams, and then provide only the necessary privileges to each team.
This should be done by the organization admin. After creating a team, it can be given a permission to have access to Design, Transition and Operations phases.
Do not make every user an admin. Admin access should be limited to selected users in an organization.
Enable Access to an Assembly for a User on a Team