Sub Macro1()
'Graham Mayor - https://www.gmayor.com - Last updated - 02 Dec 2020
Dim i As Integer
Dim oStory As Range
    For Each oStory In ActiveDocument.StoryRanges
        For i = oStory.Fields.Count To 1 Step -1
            If oStory.Fields(i).Type = wdFieldRef And _
               oStory.Fields(i).Result = "Error! Reference source not found." Then
                oStory.Fields(i).Delete
            End If
        Next i
        If oStory.StoryType <> wdMainTextStory Then
            While Not (oStory.NextStoryRange Is Nothing)
                Set oStory = oStory.NextStoryRange
                For i = oStory.Fields.Count To 1 Step -1
                    If oStory.Fields(i).Type = wdFieldRef And _
                       oStory.Fields(i).Result = "Error! Reference source not found." Then
                        oStory.Fields(i).Delete
                    End If
                Next i
            Wend
        End If
    Next oStory
lbl_Exit:
    Set oStory = Nothing
    Exit Sub
End Sub