post https://keyauth.win/api/1.2/?type=changeUsername&newUsername=&sessionid=&name=&ownerid=
Allow users to change their usernames
The user must be logged in (the session has to be validated) to change the username.
If successful username change, the session is made invalid and the user will need to log in with their username if they want to send any more requests to KeyAuth.
Code Example
KeyAuthApp.changeUsername(username);
KeyAuthApp.changeUsername(username);