undo a commit done in github code example

Example 1: github restore previous commit

# syntax
git revert <commit>
# example
git revert 99a5c5905e12c74725bae64c61efce140662ce24
# where 99a5c59... is the commit (you can check it on github)

Example 2: github cancel last push

# to undo a git push
git push -f origin HEAD^:master

# to get to previous commit (preserves working tree)
git reset --soft HEAD

# to get back to previous commit (you'll lose working tree)
git reset --hard HEAD^