Only a supe radmin can assign another user as super admin.

From Make a user an admin

Make a user a super admin You're seeing steps for assigning admin roles to users at example.com.

Here's how to grant a user full access to your Admin console:

You must be signed in as a super administrator for this task.

Only a super admin can assign another user as super admin.

From Make a user an admin

Make a user a super admin 
You're seeing steps for assigning admin roles to users at example.com.

Here's how to grant a user full access to your Admin console:

You must be signed in as a super administrator for this task.