Check All checkbox should be unchecked

    function toggle(source) {
      checkboxes = document.getElementsByName('options[]');
      for (var i = 0, n = checkboxes.length; i < n; i++) {
        checkboxes[i].checked = source.checked;
      }
    }

<form class="unsubscribe_form" action="process.php" method="post">
  <input type="checkbox" class="unsubscribe-checkbox" name="options[]" id="checkbox-1-1" value="Option1">
  <label for="checkbox-1-1"></label>Option 1
  <input type="checkbox" class="unsubscribe-checkbox" name="options[]" id="checkbox-1-2" value="Option2">
  <label for="checkbox-1-2"></label>Option 2
  <input type="checkbox" class="unsubscribe-checkbox" name="options[]" id="checkbox-1-3" value="Option2">
  <label for="checkbox-1-3"></label>Option 3
  <input type="checkbox" class="unsubscribe-checkbox" name="options[]" id="checkbox-1-4" value="Option3">
  <label for="checkbox-1-4"></label>Option 4
  <input type="checkbox" class="unsubscribe-checkbox" name="options[]" id="checkbox-1-5" value="Option3">
  <label for="checkbox-1-5"></label>Option 5
  <input type="checkbox" class="unsubscribe-checkbox" id="checkbox-1-6" value="All" onClick="toggle(this)" />
  <label for="checkbox-1-6"></label>All
  <br>
  <input type="submit" name="formSubmit" value="Unsubscribe" />
</form>

When I check the All checkbox, of course, it will mark all the checkboxes, but once I uncheck one checkbox, the All checkbox is still checked. This should be unchecked. How should I do that using JS?