How do i unregister a hook function

function setTextPosHook(text)
if getObject("Conditions[hook_active]"):getBool(VConditionValue) then
 if text:getLink(VTextOwner):getId().tableId == eCharacters then
  if text:getLink(VTextOwner):getName() == "chicken" and game:getLink(VGameCurrentScene):getName() == "03_inside hut" then
    text:setValue(VTextPosition, {x= game:getPoint(VGameWindowResolution).x/2, y=500})
   end
  end
  return true
 end
end

registerHookFunction("setTextPosition", "setTextPosHook")