Código eliminar nombres externo/interno definidos

Tengo un archivo de excel con más de 400 nombre definidos que ya no se usan y no están dentro del libro (son internos como externos)... ¿me podréis ayudar a eliminarlos por favor?
He ejecutado el sig código pero me aparece error
*********************************************
Option Explicit
 Sub delete_external_names()
 'variable declarations
 Dim response As Integer
 Dim msg As String
 Dim flag As Boolean
 Dim defined_name As Object
   flag = True     ' check if external links were found
   ' loop through each defined name in workbook
   For Each defined_name In ActiveWorkbook.Names
      ' if a [ was found, then the name has a link
      If InStr(defined_name.RefersTo, "[") > 0 Then
         flag = False ' set flag to False indicating a link was found
         ' Message displayed to ask if you want to delete name
          msg = "Do you want to delete the defined name " & "'" & _
             defined_name.Name & "'" & Chr(13) & " that refers to '" & _
             defined_name & "' ?"
          ' delete the defined name
          If MsgBox(msg, 292) = vbYes Then defined_name.Delete
       End If
   Next defined_name  ' get the next defined name
   If flag = True Then  ' if flag was not set, display message below
      MsgBox "No defined names with external were links found."
   End If
 End Sub
*****************************************
help