Your username was set up for you when you joined Plan Hero plan managers, and was sent via email called "Welcome to Planability with Plan Hero Pty Ltd".
You cannot reset your username, however if you have forgotten it not to worry. Simply click the button below 'Login' and then click 'Forgot Username'?
You will then be prompted to enter your email and you will be sent email instructions on how to reset your password. (Make sure you check your junk email too).