This is an easy way to change the username of your wordpress admin account:

• login as your current admin user
• navigate to users > all users
• add a new user
• make sure the role is ‘administrator’
• give the user the desired username that you want

the next steps are:

• logout of your current admin account
• log back in as your new admin user
• navigate to users > all users
• delete your old admin user.

WordPress will now ask what you want to do with the posts created by your old admin user. Simply pick your new admin users name from the drop down list and assign them all to your new user.

you now have a new administrator account with a different username :D