public void DeleteBetweenBoomarks(String start, String end)
        {
            Microsoft.Office.Interop.Word.Application _app = new Microsoft.Office.Interop.Word.Application();
            Microsoft.Office.Interop.Word.Document _doc = _app.Documents.Open("pfad");

            if (BookmarkExists(start) && BookmarkExists(end))
            {
                Range range = _doc.Range( _doc.Bookmarks[start].Range.Start,_doc.Bookmarks[end].Range.End);
                range.Select();
                range.Delete();
            }
        }