Add Administrators to Your Community
Can I add additional administrators in my community?
Yes, depending on license type, a community owner may assign UNLIMITED additional admins to their community.
How do I add additional administrators in my community?
By default, admins of the community are listed with their avatars between the Submit New Idea button and the homepage idea overview:

Clicking the "+ Administrator" allows you to add an additional admin, where additional admins will appear in the order in which they were added. The owner can click the "X" in the corner of the additional admin's avatar to remove/unassign the additional admin as easily as it was assigned.

What is the difference between the primary admin (the community owner) and additional admins?
The additional admins have all the privileges of the primary
admin EXCEPT:
1. Additional admins can not create new communities.
2. Additional admins can not assign additional admins.
If I am the primary admin and community owner, can I relinquish/transfer ownership privileges to another community admin that I assign?
Because primary admins are associated with the billing of the community, it is not presently possible to transfer the primary admin role.