In the Java version of iText, there's a method
getPageEvent() available in
PdfWriter. There should be a
PageEvent in iTextSharp that you can use to find out if there is a page event present.
To remove an existing page event, you need to set the page event to
null. Adding an extra page event won't replace the existing page event, but add an extra event that will be triggered along with the original event(s).