Hi,
Please refer below code.
HTML
<script type="text/javascript">
function CloseWindow() {
window.close();
}
</script>
<asp:Button Text="Close" runat="server" OnClick="Close" />
C#
protected void Close(object sender, EventArgs e)
{
Page.ClientScript.RegisterOnSubmitStatement(typeof(Page), "closePage", "window.onunload = CloseWindow();");
}
or you can use
Response.Write("<script language=javascript>this.window.opener = null;window.open('','_self'); window.close();</script>");
I hope this will help you out.