Re: changing admin name block access
Set your current new user to be the Site admin user.
You will need access to the database, look in wp_sitemeta for a line with a meta_key of site_admins. It will currently look like:
You need to change the admin to be your new users name, and the s:5 to be the length of your new user. E.G.
spacetest is nine characters long so I’ve changed s:5 – s:9
When you next login your new user will be the site admin user, and you can access the plugins menu.
From wordpress MU post: