Not very ellegant but it works:-
Dim TempString As String, i As Integer
YourString = "000 000 000 000"
TempString = ""
For i = 1 To Len(YourString)
If Mid(YourString, i, 1) <> Chr(32) Then
TempString = TempString & Mid(YourString, i, 1)
End If
Next i
YourString = TempString