undoer
nounUK /ʌnˈduːə/
US /ʌnˈduːər/
A person who takes apart or cancels something that was done.
The undoer of the knot finally freed the tangled rope.
OTHER MEANINGS
2. A person who brings ruin or destruction to someone or something.
He was seen as the undoer of the family business.
3. A tool or device used to loosen or unfasten something.
She used a small undoer to open the tight jar lid.
4. In computing, a function or command that reverses a previous action.
The undoer restored the deleted paragraph.