Update the URL of origin remote like, using SSH instead HTTPS;
git remote set-url origin git@github.com:username/repo.git
You can also use;
git config --global credential.helper store
to make git store the username and password and it will never ask for them.
You can save the username and password for a session (cache it);
git config --global credential.helper cache
You can change the timeout for above setting using;
git config --global credential.helper 'cache --timeout=600'