The following is a modification of some code I created a while ago that
should do that.  Don't use it until you are really finished with creating
the document, or run it on a copy of the document as it turns the end notes
into ordinary text and if you later add one, it will be treated as the first
end note in the document.

' Macro created 29/09/99 by Doug Robbins to replace endnotes with textnotes
at end of document
' to replace the endnote reference in the body of the document with a
superscript number.
'
   Dim aendnote As Endnote
   Dim refrange As Range
   Dim i As Long
   For Each aendnote In ActiveDocument.Endnotes
       Set refrange = aendnote.Reference
       refrange.Start = ActiveDocument.Range.Start
       i = refrange.Sections.Count
       ActiveDocument.Range.InsertAfter vbCr & i & " - " & aendnote.Index &
vbTab & aendnote.Range
       aendnote.Reference.InsertBefore "a" & aendnote.Index & "a"
   Next aendnote
   For Each aendnote In ActiveDocument.Endnotes
       aendnote.Reference.Delete
   Next aendnote
   Selection.Find.ClearFormatting
   Selection.Find.Replacement.ClearFormatting
   With Selection.Find.Replacement.Font
       .Superscript = True
   End With
   With Selection.Find
       .Text = "(a)([0-9]{1,})(a)"
       .Replacement.Text = "\2"
       .Forward = True
       .Wrap = wdFindContinue
       .Format = True
       .MatchWildcards = True
   End With
   Selection.Find.Execute Replace:=wdReplaceAll