using(var doc = PdfDocument.Load(@"e:\ABWORK\_Projects\PDFAnnotator\Shared.Tests\Files\test002.pdf", new PdfForms()))
{
    var field = doc.FormFill.InterForm.Fields.Single(item => item.FullName == "Column6_Szn77rtV*0hjPOwPY0vuDA");
    var dict = doc.FormFill.InterForm.Dictionary;
    var fieldsArray = dict["Fields"].As<PdfTypeArray>();
    var refToField = fieldsArray.Single(item => item.As<PdfTypeDictionary>().Handle == field.Dictionary.Handle);

    foreach (var page in doc.Pages)
    {
        if (page.Annots == null)
            continue;
        foreach (var ctrl in field.Controls)
        {
            var annot = page.Annots.GetByDictionary(ctrl.Dictionary);
            if (annot != null)
                page.Annots.Remove(annot);
        }
    }
    fieldsArray.Remove(refToField);
              
    doc.Save(@"e:\36\test.pdf", SaveFlags.NoIncremental | SaveFlags.RemoveUnusedObjects);
}