vbCrLf and vbNewLine are actualy two characters long, so change to Right$(myString, 2)
Sub linebreak(myString)
If Len(myString) <> 0 Then
If Right$(myString, 2) = vbCrLf Or Right$(myString, 2) = vbNewLine Then
myString = Left$(myString, Len(myString) - 2)
End If
End If
End Sub