Hi there! 👋 Welcome to the Community!

Unfortunately because it’s treated by our system as the same name, you can either:

• Change your username to something else entirely and then change it back to the lowercase version. Username changes are typically more or less instant.

or

• If you worry your username might get nabbed while you are making the switch, you can get in touch with support and we can make the change directly. Please note: this will require more patience than the DIY option 😉

https://support.github.com/contact