How to Create WPMu New User?

You will need to give user2 Super Admin privileges by directly modifying the database.

Run this query in phpMyAdmin:

SELECT * FROM wp_sitemeta where meta_key='site_admins';

This is an array of all your Super Admins. It should return something like this:

a:1:{i:0;s:5:"user1";}

Note that 5 is the length of string ‘user1’. Here is an example modification to make ‘username2’ the Super Admin:

a:1:{i:0;s:9:"username2";}