How to compress WinForms PDF using C# and VB.NET?

using Syncfusion.Pdf;
using Syncfusion.Pdf.Parsing;

Imports Syncfusion.Pdf
Imports Syncfusion.Pdf.Parsing

// [C# Code]
// Loads an existing PDF document
PdfLoadedDocument loadedDocument = new PdfLoadedDocument(inputFile);
// Create new PDF compression options
PdfCompressionOptions options = new PdfCompressionOptions();
// Compress image
options.CompressImages = true;
options.ImageQuality = 50;
// Compress the font data
options.OptimizeFont = true;
// Compress the page contents
options.OptimizePageContents = true;
// Remove the metadata information
options.RemoveMetadata = true;
// Set the options to loaded PDF document
loadedDocument.CompressionOptions = options;
// Restructure the document
loadedDocument.FileStructure.IncrementalUpdate = false;
// Remove form fields and their data
RemoveFormFields(loadedDocument, false);
// Remove annotations and their data
RemoveAnnotations(loadedDocument, false);
// Save the document
loadedDocument.Save("Sample.pdf");
// Close the document
loadedDocument.Close(true);
// This will open the PDF file, so the result will be seen in the default PDF viewer
Process.Start("Sample.pdf");

// Remove form fields and their data
private void RemoveFormFields(PdfLoadedDocument loadedDocument, bool value)
{
    if (!value)
    {
        int totalFieldCount = loadedDocument.Form.Fields.Count;
        for (int i = totalFieldCount - 1; i >= 0; i--)
        {
            PdfField field = loadedDocument.Form.Fields[i] as PdfField;
            if (field != null)
            {
                loadedDocument.Form.Fields.Remove(field);
            }
        }
    }
}

// Remove annotations and their data
private void RemoveAnnotations(PdfLoadedDocument loadedDocument, bool value)
{
    if (!value)
    {
        PdfLoadedAnnotationCollection collection = null;
        for (int j = 0; j < loadedDocument.Pages.Count; j++)
        {
            collection = loadedDocument.Pages[j].Annotations;
            int totalAnnotationCount = collection.Count;
            for (int i = totalAnnotationCount - 1; i >= 0; i--)
            {
                collection.RemoveAt(i);
            }
        }
    }
}

' [VB Code]
' Loads an existing PDF document
Dim loadedDocument As New PdfLoadedDocument(inputFile)
' Create new PDF compression options
Dim options As New PdfCompressionOptions()
' Compress image
options.CompressImages = True
options.ImageQuality = 50
' Compress the font data
options.OptimizeFont = True
' Compress the page contents
options.OptimizePageContents = True
' Remove the metadata information
options.RemoveMetadata = True
' Set the options to loaded PDF document
loadedDocument.CompressionOptions = options
' Restructure the document
loadedDocument.FileStructure.IncrementalUpdate = False
' Remove form fields and their data
RemoveFormFields(loadedDocument, False)
' Remove annotations and their data
RemoveAnnotations(loadedDocument, False)
' Save the document
loadedDocument.Save("Sample.pdf")
' Close the document
loadedDocument.Close(True)
' This will open the PDF file, so the result will be seen in the default PDF viewer
Process.Start("Sample.pdf")

' Remove annotations and their data
Private Sub RemoveAnnotations(loadedDocument As PdfLoadedDocument, value As Boolean)
    If Not value Then
        Dim collection As PdfLoadedAnnotationCollection = Nothing

        For j As Integer = 0 To loadedDocument.Pages.Count - 1
            collection = loadedDocument.Pages(j).Annotations
            Dim totalAnnotationCount As Integer = collection.Count

            For i As Integer = totalAnnotationCount - 1 To 0 Step -1
  
                collection.RemoveAt(i)
            Next
        Next
    End If
End Sub

' Remove form fields and their data
Private Sub RemoveFormFields(loadedDocument As PdfLoadedDocument, value As Boolean)
    If Not value Then
        Dim totalFieldCount As Integer = loadedDocument.Form.Fields.Count
        For i As Integer = totalFieldCount - 1 To 0 Step -1
            Dim field As PdfField = TryCast(loadedDocument.Form.Fields(i), PdfField)
            If field IsNot Nothing Then
                loadedDocument.Form.Fields.Remove(field)
            End If
        Next
    End If
End Sub