undo

verb (used with object), un·did, un·done, un·do·ing.

1. to reverse the doing of; cause to be as if never done: Murder once done can never be undone.
2. to do away with; erase; efface: to undo the havoc done by the storm.
3. to bring to ruin or disaster; destroy: In the end his lies undid him.
4. to unfasten by releasing: to undo a gate; to undo a button.
5. to untie or loose (a knot, rope, etc.).
6. to open (a package, wrapping, etc.).
7. Archaic. to explain; interpret.

verb -does, -doing, -did or -done (mainly tr)

1. (also intr) to untie, unwrap, or open or become untied, unwrapped, etc
2. to reverse the effects of
3. to cause the downfall of
4. obsolete to explain or solve

v.Old English undon “to unfasten and open” (a window or door), “to unfasten by releasing from a fixed position,” from un- (2) + do (v.). The notion is of “to annul something that was done.” Related: Undone; undoing.