How do I change my wordpress username?

You’ll need to use phpMyAdmin

See this guide from Podz to get started:

https://tamba2.org.uk/wordpress/phpmyadmin/

Only you need to edit is the “user_login” field rather than the password.

Usual safety procedures apply: make sure you have a backup of the database before twiddling it. I’ve done this several times without any problems, but…

I do not have phpmyadmin. How do I use it?

If you don’t have a way to ‘manipulate’ (i.e. phpMyAdmin) the database as Les suggested, then create a new user, give that user the Administrator Role and use that login from now on. If necessary, then change the author on your posts to the new user.

This assumes you have shell access via SSH or telnet.

At the command line do (change things to suit your environment)

mysql –user=your_user_name –password=your_password db_name

then

update your_wp_prefix_users set user_login=’newadmin_name’ where user_login=’admin’;