code: @Override
    public void deselectByValue(String value) {
      if (!isMultiple()) {
        throw new UnsupportedOperationException(
          "You may only deselect options of a multi-select");
      }
  
      for (WebElement option : findOptionsByValue(value)) {
        setSelected(option, false);
      }
    }
docs: Deselect all options that have a value matching the argument. That is, when given "foo" this
  would deselect an option like:
  
  &lt;option value="foo"&gt;Bar&lt;/option&gt;
  
  @param value The value to match against
  @throws NoSuchElementException If no matching option elements are found
  @throws UnsupportedOperationException If the SELECT does not support multiple selections