Remove values from select list based on condition

Answer 1

You may use:

if ( frm.product.value=="F" ){
    var $select_box = $('[name=val]');
    $select_box.find('[value=A],[value=C]').remove(); 
}

Update: If you modify your select box a bit to this

<select name="val" size="1" >
  <option id="A" value="A">Apple</option>
  <option id="C" value="C">Cars</option>
  <option id="H" value="H">Honda</option>
  <option id="F" value="F">Fiat</option>
  <option id="I" value="I">Indigo</option>                    
</select> 

the non-jQuery solution would be this

if ( frm.product.value=="F" ){
    var elem = document.getElementById('A');
    elem.parentNode.removeChild(elem);
    var elem = document.getElementById('C');
    elem.parentNode.removeChild(elem);
}