How to add a new super-admin to a WordPress multisite
WordPress multisite has an additional admin role above regular admin, called the super-admin. Regular admin user can manage and administrate a single WordPress site and the super-admin user has admin rights to all sites under the multisite installation.
You can create a new super-admin user to your WordPress multisite by navigating to My sites - network management - users menu and selecting the 'Add user' button. After adding the new user you can change their user role from the edit user menu.
Start by navigating to the Users menu.
Click on the 'Add New' button to add a new user.
Enter the Username and Email for the new user. After the user is added an email will be sent to them with a link for setting up a password,
After the user is added, click on the 'Edit user' link in the view that opened up.
From the menu that opens up, scroll down to the 'Super Admin' -option, and select the 'Grant this user super admin privileges for the Network' checkbox. Finally, click on the 'Update User' button at the bottom of the menu.
Now the new super-admin user has been added to the Network and they can start managing all the sites under the Network.