Definitions of undo:

• verb:   cause the ruin or downfall of
• verb:   cancel, annul, or reverse an action or its effect

  Example: "I wish I could undo my actions"

• verb:   remove the outer cover or wrapping of

  Example: "Undo the parcel"

• verb:   cause to become loose

  Example: "Undo the shoelace"

• verb:   deprive of certain characteristics