Note Within 30 days of creating your gamertag, you can change it once for free. To do this, sign in to your account on live.xbox.com, click My Profile, click EDIT MY PROFILE, then click Change gamertag.
After 30 days, you’ll have to change your gamertag on your Xbox console, and the change will cost extra. To to this, follow the steps on this page.
Change your gamertag
On your Xbox console, go to social, then select Sign In or Out.
Select your profile to sign in.
Scroll right to settings, then select Profile.
Select Edit Profile.
Select Enter New Gamertag.
Type a new gamertag (up to 15 characters), then select Done.
If the gamertag you enter is already taken, you will be prompted to try another gamertag.
Once you enter or select a new gamertag, select Yes, use this gamertag.
Once you confirm your new gamertag, the change is reflected across Xbox Live. You don’t need to tell your friends that you changed your gamertag — their friends lists will be updated automatically.