Select mother department (here "Internal") - will be marked in bold text
Add department by selecting 3 dots
Enter Department name
Create
Edit department - change name, delete
Select department (here: "Department A") - will be marked in bold text)
Select 3 dots
Select "Edit properties"
Change the name of the department
Update
Delete department: select delete. If the delete option is not there, you have roles added in the department. If you still want to delete the department, you first have to move or remove the roles.