Hi,
Here I have created sample that will help you out.
HTML
<div>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
<script type="text/javascript">
function ClearDatalist() {
$("[id*=ddlist_rooms] tr:not(:first-child)").remove();
return false;
}
</script>
<asp:DataList ID="ddlist_rooms" runat="server" RepeatColumns="1" RepeatLayout="Table">
<HeaderTemplate>
Rooms & Rates
</HeaderTemplate>
<ItemTemplate>
<div>
<span class="roomtype">
<%# Eval("room_type") %></span></u></b>
</div>
<div>
Price: </b><span class="rate">
<%# Eval("rate") %></span><br />
</div>
</ItemTemplate>
</asp:DataList>
<asp:Button Text="Clear" runat="server" OnClientClick="return ClearDatalist()" />
</div>