Before you proceed, you need Spaces installed on your phone.
How to set a member as Admin?
Step 1 - Open the Space for which you want to set a member as Admin and Navigate to the Members Tab.
Step 2 - In the members' tab, select the member you want to give the Admin rights.
Step 3 - Click on Set as Admin.
Step 4 - It would open a confirmation screen, here click to confirm for Set as Admin.
You are done!