You can undo git add before commit with
git reset <file>
You can use
git reset
without any file name to unstage all due changes. This can come in handy when there are too many files to be listed one by one in a reasonable amount of time.
check this article
To undo the most recent commit I do this:
First:
git log
get the very latest SHA id to undo.
git revert SHA
That will create a new commit that does the exact opposite of your commit. Then you can push this new commit to bring your app to the state it was before, and your git history will show these changes accordingly.
Check this answer on stack overflow