Hello johnvrsm,

The code that you can use to clear items on Client-Side is shown below:

<ig:WebDropDown ID="WebDropDown2" runat="server" Width="200px">
   <Items>
         <ig:DropDownItem Selected="False" Text="Item0" Value="0">
         </ig:DropDownItem>
         <ig:DropDownItem Selected="False" Text="Item1" Value="1">
         </ig:DropDownItem>
         <ig:DropDownItem Selected="False" Text="Item2" Value="2">
         </ig:DropDownItem>
   </Items>
</ig:WebDropDown>
<input id="Button2" type="button" value="Clear Items" onclick="clearDDItems()" />
 
<script type="text/javascript">
 
function clearDDItems() {
 
    var dropdown = $find("WebDropDown2");
 
            
    dropdown._elements["List"].innerHTML = '';
 
 
    dropdown.set_currentValue("", true);                         
}
    
</script>
 

This code will clear the items from the dropdown but since this is a Server control to remove items entirely you will have to clear items from Server collection also.