Only the system admin can setup the department hierarchy.
The system admin can create any number of top level departments and create any levels of sub-departments under each department. And each level of department can be populated with members. The system admin can set the role of each member to 'member' or 'admin'. System admin can also delete a department after all the sub-departments and libraries are deleted.
To create a department:
1. Go to the system admin interface: click the person icon at the top right corner and click Organization Admin
2. Click Departments on the left panel.
3. Click New Department.
To create a sub-department:
1. Click on the department in the Departments section in the system admin interface.
2. Click New Sub-department.
To add members to the department(or sub-department):
1. Click on the department in the Departments section(then click on the sub-department) in the system admin interface.
2. Click Add Member, then search for the users and click Submit.