Find the git commit you want to rollback to:
git log -n20
git checkout <commit hash>
Then do:
git reset --hard <commit hash>
git push -—force
Note this can inconvenience some users because they can end up with conflicts since you did a a forced push.
So another approach after checking your commit, is to create a new branch and then create a PR to merge in the rollbacked code:
git checkout -b rollbacked-code
git push # then create a PR