Very basic but i dont know

any one knw how to change username

you want to change username of form right?
you have to message as you want it to be change there is no way you can do it by yourself just text them they will change it for you

You could probably ask for help at gitter chat of Freecodecamp.

I have moved your thread to the #support topic, you need to say what username you want and a moderator may be willing to change your username