Change GitHub Account username

Yes, it's possible. But first read, "What happens when I change my username?"

To change your username, click your profile picture in the top right corner, then click Settings. On the left side, click Account. Then click Change username. See the pictures below: Settings

Change username

Confirm changing username

Type the new username

Confirm the new username

Yes, this is an old question. But it's misleading, as this was the first result in my search, and both the answers aren't correct anymore.

You can change your Github account name at any time.

To do this, click your profile picture > Settings > Account Settings > Change Username.

Links to your repositories will redirect to the new URLs, but they should be updated on other sites because someone who chooses your abandoned username can override the links. Links to your profile page will be 404'd.

For more information, see the official help page.

And furthermore, if you want to change your username to something else, but that specific username is being taken up by someone else who has been completely inactive for the entire time their account has existed, you can report their account for name squatting.