To reverse, as what has been done; to annul; to bring to naught.
To loose; to open; to take to piece; to unfasten; to untie; hence, to unravel; to solve; as, to undo a knot; to undo a puzzling question; to undo a riddle.
To bring to poverty; to impoverish; to ruin, as in reputation, morals, hopes, or the like; as, many are undone by unavoidable losses, but more undo themselves by vices and dissipation, or by indolence.
I'm not gonna try to defend, or undo what's been done. All I could say about whatever's been done, it's been done, and it's water under the bridge. I have no regrets of my life. Ike Turner
We cannot turn the clock back nor can we undo the harm caused, but we have the power to determine the future and to ensure that what happened never happens again. Paul Kagame
You can't undo the past... but you can certainly not repeat it. Bruce Willis
Pope Benedict is an amazingly visionary person. What he has done is establish an evolutionary process that will help undo the Reformation. The Anglican Church has been hijacked by modernism, with synods trying to amend the faith and this process will allow traditional Anglicans to be themselves. Peter Slipper
My grandmother though, began to prepare in her own neurotic - and I think psychotic - way to face racism. So she taught us to be racist, which is something I had to undo later when I got to Michigan, you know. James Earl Jones