Why can't I change the user on github?

Question

git

I had an old account on github, from there I pushed and pushed everything. Created a new account, changed everything as it should.

git config --global user.name "example"
$ git config --global user.email example

For some reason, when I push, he climbs to the old Heartprogrammer user, and I have a new zoxon470.

MacBook-Pro-Ahmed:kstu_project HeartProgrammer$ git add .
MacBook-Pro-Ahmed:kstu_project HeartProgrammer$ git commit -m "initial commit"
[master 161c992] initial commit
 1 file changed, 0 insertions(+), 0 deletions(-)
 delete mode 100644 readme.txt
MacBook-Pro-Ahmed:kstu_project HeartProgrammer$ git push -u origin master
remote: Permission to zoxon470/library.git denied to HeartProgrammer.
fatal: unable to access 'https://github.com/zoxon470/library.git/': The requested URL returned error: 403
MacBook-Pro-Ahmed:kstu_project HeartProgrammer$