Commit

Revert Commit

git log ( get hash few characters )
git revert <git hash (few char)>
git revert HEAD ( revert to last commit )

Alter commit history

Warning! - never want to do when changes pushed and used by other devs

// add new changes to recent commit without modifying commit message
git commit --amend --no-edit

// add new changes to recent commit with new commit message 
// ( recent commit message would be lost )
git commit --amend