Try something like this… jsfiddle demo
HTML
<!-- Source: -->
<select id="source" name="source">
<option>MANUAL</option>
<option>ONLINE</option>
</select>
<!-- Status: -->
<select id="status" name="status">
<option>OPEN</option>
<option>DELIVERED</option>
</select>
JS
$(document).on('ready', function () {
$("#source").on('change', function () {
var el = $(this);
if (el.val() === "ONLINE") {
$("#status").append("<option>SHIPPED</option>");
} else if (el.val() === "MANUAL") {
$("#status option:last-child").remove();
}
});
});