Once a commit is pushed, you do NOT want to use git reset to undo it - because reset will rewrite the history tree, and anyone who has already pulled that branch will have a bad tree.
Instead, we'll use git revert to make a "revert commit" (like a merge commit), which will "undo" a specific commit. So the syntax is:
git revert [HASH-TO-UNDO]
git log --oneline
f23481b (HEAD -> master, origin/master, origin/HEAD) take 3
git revert f23481b