un‧do past tense undid past participle undone third person singular undoes [transitive]
to open something that is tied, fastened or wrapped:
The screws can be undone by hand.
I undid the package carefully.
to try to remove the bad effects of something you have done:
We cannot undo the damage of a lifetime in only 30 days.
If a medicine is taken again too soon, it may undo all the good that has been done.
to remove the effect of your previous action on a computer