public void ClearContent(
    PdfRectangle rect
)

Public Sub ClearContent(
    rect As PdfRectangle
)

using (PdfDocumentProcessor pdfDocumentProcessor = new PdfDocumentProcessor())
{
    pdfDocumentProcessor.LoadDocument("Document.pdf");
    PdfPageFacade pageFacade = pdfDocumentProcessor.DocumentFacade.Pages[0];

    PdfRectangle cropBox = pdfDocumentProcessor.Document.Pages[0].CropBox;
    double halfPage = cropBox.Top / 2;

    PdfRectangle pageRectangle = new PdfRectangle(cropBox.Left, halfPage, cropBox.Right + halfPage, cropBox.Top);

    // Clear the page area
    pageFacade.ClearContent(pageRectangle);

    pdfDocumentProcessor.SaveDocument("Document_cleared.pdf");
}

Using pdfDocumentProcessor As New PdfDocumentProcessor()
  pdfDocumentProcessor.LoadDocument("Document.pdf")

  Dim pageFacade As PdfPageFacade = pdfDocumentProcessor.DocumentFacade.Pages(0)

  Dim cropBox As PdfRectangle = pdfDocumentProcessor.Document.Pages(0).CropBox
  Dim halfPage As Double = cropBox.Top / 2
  Dim pageRectangle As New PdfRectangle(cropBox.Left, halfPage, cropBox.Right + halfPage, cropBox.Top)

  ' Clear the page area
  pageFacade.ClearContent(pageRectangle)

  pdfDocumentProcessor.SaveDocument("Document_cleared.pdf")
End Using