For whatever reason I today decided to change my github username from
To match some other profiles I use that username. It seems easy to do, but be careful, it also breaks stuff.
If you also want to do that, have a look at: https://help.github.com/en/github/setting-up-and-managing-your-github-user-account/changing-your-github-username
Plus I would recommend afterwards to register your old username with a different mail address to protect from people trying to claim repository links you previously owned.