You can hide panel and controls two way.
1) using visible=true/false property
2) using jquery
Below are the explanation with example:
1) using visible=true/false property :
<asp:Panel ID="Panel1" runat="server" Visible="false">
<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
</asp:Panel>
2) using jquery
<script type="text/javascript">
$("#ctl00_contentdetails_pnl").hide();
</script>