unhook

verb3

1. •
   To remove from a hook.

   • After Aulnoye the route lay through the colliery area and past Maubeuge to Jeumont, on the Belgian border. There Eùgene unhooked and we handed the train over to a Belgian diesel. — 1961
2. •
   To unfasten by means of hooks.

   • "She was standing in front of the mirror unhooking her frock. Mrs. P., I mean." — 1938
3. •
   (informal) To unfasten the bra of (its wearer).