ho fatto diverse modifiche e sembra funzionare:
codice:
<asp:ScriptManager ID="ScriptManager1" runat="server" EnablePartialRendering="true" AsyncPostBackTimeout="900" EnablePageMethods="true" />
codice:
    <script type="text/javascript">
        function confirmDelete(id) {
            if (confirm("Are you sure to want to Delete?") == true) {
                console.log(id);
                PageMethods.DeleteNews(
                    id,
                    function (id) {
                        alert(id);
                    }
                );
            }
        }
    </script>
codice:
    <WebMethod()>
    <ScriptMethod()>
    Public Shared Function DeleteNews(ByVal id As Integer) As String
        Diagnostics.Debug.WriteLine(id)
        Return "ID:" + id.ToString
    End Function