How to find and delete text from word document

Hi,

Below is my code to search and delete text from word document , but it gives error and range can not be deleted 

Microsoft.Office.Interop.Word.Range rng1 = workDoc.Content;
                            object searchText = (object)outsideText;
                             object missing = System.Reflection.Missing.Value;
                             rng1.Find.Execute(ref searchText, ref missing, ref missing, ref missing, ref missing, ref missing, ref missing,
                                ref missing, ref missing, ref missing, ref missing, ref missing, ref missing,
                                ref missing, ref missing);
                             object ps = rng1.Start;
                             object pe = rng1.End;
                             Microsoft.Office.Interop.Word.Range rng = workDoc.Range(ref ps, ref pe);
                             rng1.Delete(ref missing, ref missing);
                             workDoc.Save();

Any suggestion ?

Thanks in advance