undoer

transitive verb undid, undone, undoing

1. 1. to release or untie (a fastening)
   2. to open (a parcel, door, etc.) by this means
2. to reverse the doing of (something accomplished); do away with; cancel; annul
3. to put an end to; bring to ruin, disgrace, or downfall
4. to upset emotionally; perturb
5. Obsolete to interpret; explain