create a new repository on github and push files on the command line

create a new repository on github first, like https://github.com/zhuby1973/play.git
remove old git info on local:
sudo rm -rf .git
init and push files:
git init
git add .
git commit -m "first commit"
git remote add origin https://github.com/zhuby1973/play.git
git push -u origin master
some commands might help to check and verify:
git remote -v
git remote rm origin
git remote set-url origin https://github.com/zhuby1973/play.git