Im sure this is an elementary question but I'd rather ask than to spend two
hours trying to figure it out.

I have the macro below:

Sub ShadingMacro()
Dim i As Integer
i = 2
Do Until IsEmpty(Cells(i, 1))
Cells(i, 1).EntireRow.Interior.ColorIndex = 15
i = i + 2
Loop
End Sub


How do I click that same command button again to undo the highlighted rows??