Undo (verb)

1. Reverse the effect of (an action or process).
2. Remove the fastening or tie of (something).

Origin:

Late middle english: from old french desundre, from latin dis- "apart" + unda "wave".

Examples:

1. She had to undo the knot in the rope.
2. He quickly undid the buttons on his shirt.
3. The new law undid the progress made by the previous administration.
4. She undid her mistake by fixing the problem.
5. He wished he could undo what he had said, but it was too late.