//Changes all authors name and email il all comits of the repo 
git filter-branch -f --env-filter "GIT_AUTHOR_NAME='Newname'; GIT_AUTHOR_EMAIL='new@email'; GIT_COMMITTER_NAME='Newname'; GIT_COMMITTER_EMAIL='new@email';" HEAD
// the comand for push is 
git push --force --tags origin 'refs/heads/master'
// hope it helped you !

ref : https://stackoverflow.com/questions/750172/how-to-change-the-author-and-committer-name-and-e-mail-of-multiple-commits-in-gi