how to set head to previous commit in git code example

Example 1: git roll back to specific commit

//Git Rollback to a specific commit via Mac terminal

//Navigate to project and open git log
cd projectname
git log --oneline

//Locate and checkout the desired commit ID
git checkout abc1234 . 

//(Type q to quit the git log)

//Stage All changes, commit with comment, and push to remote
git add -A
git commit -m "Revert commit: abc1234"
git push

Example 2: get back some commits git

git revert {commit_id}'