English definition of “undo”
/ʌnˈduː/ verb [T] (present participle undoing, past tense undid, past participle undone)
OPEN › to open something that is tied or fastened: I took off my hat and undid my coat. Can you undo this knot for me?
GET RID OF EFFECTS › to get rid of the effects of something that has been done before: Some of the damage caused by pollution cannot be undone.