I see my old GitHub username when I run "ssh git@github.com"

I created a new GitHub account with new keypair and setup everything and can do anything without any problems at my other Mac but I cant clone my repo at this mac and I see my old username (gxlrygt) when I ssh. How can I change it to my new username ?

~ root# ssh git@github.com

PTY allocation request failed on channel 0
ERROR: Hi gxlrygt! You've successfully authenticated, but GitHub does not provide shell access
Connection to 开发者_开发知识库github.com closed.

You can see this Github: SSH issues, it was helped me.

@will, sure man! The problem was, I was using my old keypair, when I logged out from my os system and logged in again, the old keypair was removed.