Out of the box, the default WordPress user is called “admin”. It's one of those defaults that I generally recommend changing as soon as you install WordPress.
Some would argue that what you use for your username doesn't really matter, because it is really easy to discover user names in WordPress. Usually, it's just a matter of viewing page source.
That is true, but even if changing the username only makes it a little more difficult, it's probably worth it, right?
Whether you are changing for security or you're just tired of the old one, will present 3 relatively simple methods of changing your username, ranging from easy (anyone can do it) to intermediate.
1) (Easy) Add a New User and Delete the Old
This is by far the easiest way to change your user name. All you need to do is:
Make a new user. Give it the new username that you want, and be sure to give that user the role of “Administrator” (very important! ). Make sure you are using a very secure password. I recommend using upper and lower case letters, numbers, and non alphanumeric characters as well. Remember, we don't want to make it easy for the hackers.
Next, you'll need to log out and log back in using the new user you just created.
Navigate to the “Users” page in the dashboard, and delete the old user. When you do this, you will be asked “What should be done with content owned by this user?”. Make sure to choose “Attribute all content to: [New User]”
Now you can click the “Confirm” button.
2) (Easy) Use a Plugin
There are several plugins available that you can use to easily change a username. Just go to the WP plugin directory and search for “Change Username”, and you'll find many options.
3) (intermediate) Change a Username via MySQL
So if you're using this method, I'll assume that you know how to access MySQL. Most people use some sort of MySQL administration app to manage MySQL. One of the more popular options is phpMyAdmin.
Login, select your database, and then execute this Query (Make sure to swap out the example names with your own):
UPDATE wp_users SET user_login = 'newName' WHERE user_login = 'admin';
And that's that. As usual, if you have any questions or comments, please leave a comment or get in touch via email or twitter.