deletedPages: [1, 2, 3],
Your server would receive this information and use PDFNet to delete and rotate those pages on the original PDF. Now that the original PDF is updated you can convert it to XOD using PDFNet and then if you like you can notify WebViewer to load the new XOD document.
It's up to you to implement a server end point that can receive messages like I mentioned above and run the necessary PDF code to update the PDF. Hopefully that clarifies what we're describing, but let us know if you have any further questions.
PDFTron Systems Inc.