How to edit text in an existing PDF

I have a PDF document and have a page number at specific position. I would like to update the page numbers. Please refer the attached documents. source.pdf and expected.pdf.

expected.pdf (167.9 KB)
source.pdf (116.6 KB)

@Sri79,

You can overwrite the page number stamp on each page with the White background color. Please try the code as follows:
C#

string dataDir = @"C:\Pdf\test821\";
// Open document
Document pdfDocument = new Document(dataDir + "source.pdf");

// Create page number stamp
PageNumberStamp pageNumberStamp = new PageNumberStamp();
// Whether the stamp is background
pageNumberStamp.Background = false;
pageNumberStamp.Format = "Page #";// of " + pdfDocument.Pages.Count;
pageNumberStamp.BottomMargin = pdfDocument.Pages[1].Rect.Height - 50;
pageNumberStamp.RightMargin = 65;
pageNumberStamp.HorizontalAlignment = HorizontalAlignment.Right;
pageNumberStamp.StartingNumber = 1;
// Set text properties
pageNumberStamp.TextState.Font = FontRepository.FindFont("Arial");
pageNumberStamp.TextState.FontSize = 12.0F;
pageNumberStamp.TextState.FontStyle = FontStyles.Bold;

pageNumberStamp.TextState.ForegroundColor = Aspose.Pdf.Color.Black;
pageNumberStamp.TextState.BackgroundColor = Aspose.Pdf.Color.White;

foreach(Aspose.Pdf.Page page in pdfDocument.Pages)
    // Add stamp to particular page
    page.AddStamp(pageNumberStamp);
            
// Save output document
pdfDocument.Save(dataDir + "Output.pdf");

This is the output PDF file: Output.pdf (143.6 KB)