How to change the Username of Hotmail account
Step 1: Sign in your account via https://outlook.live.com, using your current username and password. On the outlook homepage, you could see your email options on the left and your profile information on the right. Click on your username, the number of email setting options will be available to you.
Step 2: Click "Edit profile". You could freely change your personal profile including your websites; you’re working experiences, education, and contact information.
Step 3: Click "Edit" next to your username.
Step 4: Enter both First name and Last name. Click "Save” to maintain all of your changes, and then you will be prompted to the homepage. Your new username will be updated immediately.