Public Shared Sub TestRemoveTextOnAllPages(inputPdfFilename As String, outputPdfFilename As String)
    ' open document
    Using document As New Vintasoft.Imaging.Pdf.PdfDocument(inputPdfFilename)
        ' for all pages
        For Each page As Vintasoft.Imaging.Pdf.Tree.PdfPage In document.Pages
            Dim rect As System.Drawing.RectangleF = page.MediaBox
            rect.Inflate(New System.Drawing.SizeF(-rect.Width / 4, -rect.Height / 4))
            ' remove text that containts with specified rectangle on PDF page
            page.RemoveText(rect)
        Next
        ' pack document
        If inputPdfFilename = outputPdfFilename Then
            document.Pack()
        Else
            document.Pack(outputPdfFilename)
        End If
    End Using
End Sub

public static void TestRemoveTextOnAllPages(string inputPdfFilename, string outputPdfFilename)
{
    // open document
    using (Vintasoft.Imaging.Pdf.PdfDocument document = new Vintasoft.Imaging.Pdf.PdfDocument(inputPdfFilename))
    {
        // for all pages
        foreach (Vintasoft.Imaging.Pdf.Tree.PdfPage page in document.Pages)
        {
            System.Drawing.RectangleF rect = page.MediaBox;
            rect.Inflate(new System.Drawing.SizeF(-rect.Width / 4, -rect.Height / 4));
            // remove text that containts with specified rectangle on PDF page
            page.RemoveText(rect);
        }
        // pack document
        if (inputPdfFilename == outputPdfFilename)
            document.Pack();
        else
            document.Pack(outputPdfFilename);
    }
}