<!DOCTYPE html>
<html>
<body>

<form>
<select id="mySelect" size="4">
  <option>Apple</option>
  <option>Pear</option>
  <option>Banana</option>
  <option>Orange</option>
</select>
</form>
<br>

<button onclick="myFunction()">Remove option with index "2"</button>

<script>
function myFunction() {
    var x = document.getElementById("mySelect");
    x.remove(2);
}
</script>

</body>
</html>