Change user name

No you can’t change that field, but you can create a new user with the username you desire, then delete the old unwanted username and assign that user’s posts to the new user.

I guess you are referring to the admin name right? As MichaelH said you can just create a new user with administrator role and you are set, but if you really really want to change it you can do it in phpMyAdmin, here’s how

You can probably access phpMyAdmin through your website cpanel.

I just used the phpMyAdmin method. No problems.