This guide will walk you through updating your WordPress username via phpMyAdmin.
Unfortunately WordPress does not have this functionality in built so you can only make these updates manually via phpMyAdmin or by installing the Username Changer plugin to automate this process. The Username Changer plugin is available at WordPress.org.
1. Firstly, login to your cPanel account. If you have forgotten your cPanel credentials, they were included in the original Welcome to Serversaurus email which you should be able to find in your inbox otherwise follow these instructions on how to update your cPanel password.
2. Using the Find bar in cPanel, search for phpMyAdmin.
3. Now you have opened phpMyAdmin, select the database associated with your WordPress install on the left hand side of the page, to view a list of the current database tables.
4. Now, select wp_users from the tables list.
5. Update the fields user_login, user_nicename and display_name with your new username, just double click the text area to edit the existing text.
Now you should be able to login to /wp-admin with your new username.