Função para remover caracteres não numéricos de um texto.
Sub teste()
    Range("A2").Value2 = RemoveCaracterNaoNumericos(Range("A1").Value2)
End Sub
Function RemoveCaracterNaoNumericos(ByVal AlphaNum As Variant) As String
         Dim Clean As String
         Dim Pos, A_Char$
         Pos = 1
         If IsNull(AlphaNum) Then Exit Function
         For Pos = 1 To Len(AlphaNum)
            A_Char$ = Mid(AlphaNum, Pos, 1)
            If A_Char$ >= "0" And A_Char$ <= "9" Then
              Clean$ = Clean$ + A_Char$
            End If
         Next Pos
         RemoveCaracterNaoNumericos = Clean$
End Function