Once you have claimed your school, you can add administrators to the system. To do this you click on the admins section of school page:
After clicking invite administrator - an overview box will appear and you enter the email address.
They will receive an email with the subject line: You’ve been invited to be a coordinator
from noreply@ustamail.com . They will need to click on Accept invite.
Once accepted, they will be listed as admins. As below.
To remove admins, you click on the trash can next to the name and follow the prompts.
More information on roles is in this article : High Schools- Administrators Access and Roles