The unbind(eventName) method of the HTML5 Report Viewer

Unbinds event handlers from the specified event.

function onPageReady(e) {
    console.log('page ready!');
}
var reportViewer = $("#reportViewer1").data("telerik_ReportViewer");
reportViewer.bind(telerikReportViewer.Events.PAGE_READY, onPageReady);
reportViewer.bind(telerikReportViewer.Events.PAGE_READY, function (e) {
    console.log('page ready from anonymous function');
});

// later
reportViewer.unbind(telerikReportViewer.Events.PAGE_READY); // this will unbind ALL event handlers, including the anonymous.