You may wish to change the email address associated with your account in the DNN Customer Success Portal, for instance because your company recently changed their name/branding, or got acquired by another company, which resulted in your email address domain being changed. You wish to know whether updating your email address will change your username as well.
Changing the email address in the DNN Success Network portal will not change the username. In fact, the username can never be changed once it is set. See the screenshot below: