How to remove Graphic zone types from a PDF while using LEADTOOLS OCR

// Create an instance of the engine 
using (IOcrEngine ocrEngine = OcrEngineManager.CreateEngine(OcrEngineType.Advantage, false))
{
   // Start the engine using default parameters 
   ocrEngine.Startup(null, null, null, @"C:\LEADTOOLS 19\Bin\Common\OcrAdvantageRuntime");


   // Create an OCR document 
   using (IOcrDocument ocrDocument = ocrEngine.DocumentManager.CreateDocument())
   {

      RasterImage image = ocrEngine.RasterCodecsInstance.Load(input, 0, CodecsLoadByteOrder.Rgb, 1, -1);
      
      // Add this image to the document 
      IOcrPage ocrPage = ocrDocument.Pages.AddPage(image, null);
      

      // Perform default AutoZoning on the page 
      ocrPage.AutoZone(null);

      foreach (OcrZone zone in ocrPage.Zones)
      {
         if (zone.ZoneType == OcrZoneType.Graphic)
         {
            ocrPage.Zones.Remove(zone);
            break;
         }
      }

      // Save the zones
      ocrPage.SaveZones(@"SAVE LOCATION.ozf");


      foreach (OcrZone ocrZone in ocrPage.Zones)
      {
         int index = ocrPage.Zones.IndexOf(ocrZone);                  
         Console.WriteLine("Zone index: {0}", index);
         Console.WriteLine("  Id                  {0}", ocrZone.Id);
         Console.WriteLine("  Bounds              {0}", ocrZone.Bounds);
         Console.WriteLine("  ZoneType            {0}", ocrZone.ZoneType);
         Console.WriteLine("----------------------------------");
      }

      //Recognize Page
      //ocrPage.Recognize(null);
      ocrDocument.Pages.Recognize(null);
      ocrDocument.Save(output, DocumentFormat.Text, null);
   }

   // Shutdown the engine 
   // Note: calling Dispose will also automatically shutdown the engine if it has been started 
   ocrEngine.Shutdown();
}