To manage administrative privileges, simply head over to the Configuration tab and click on Roles.
Select the appropriate employee, click on "Change Role" → choose "Administrator" → press Save.
The second way is tab Configuration → People → Choose an employee → Choose action (...) → Roles change → Edit → Save:
If you haven't yet added a user profile to which you'd like to assign administrator privileges, check out the article on adding new users.
💡TIP: In Calamari, there is no limit to the number of Administrators.