Please be informed that the option to change the username is a limitation of WordPress default settings and it is also not available on our platform. For now, this will require custom work. 

It’s not possible to change your username in WordPress using the same method as changing your full name or password. You can check this link that might be able to help you to change your username on your WordPress site:

https://www.wpbeginner.com/wp-tutorials/how-to-change-your-wordpress-username/