Right now if I click Button A, Button B shows a DropShadow effect:

 Private Sub ButtonA_Click(ByVal sender As System.Object, ByVal e As System.Windows.RoutedEventArgs) Handles ButtonA.Click

 Dim objDropShadow As New DropShadowEffect

            objDropShadow.ShadowDepth = 0

            objDropShadow.BlurRadius = 30

            objDropShadow.Color = Colors.GreenYellow

            Me.ButtonB.Effect = objDropShadow

End Sub

If I clicked Button C how would I remove the DropShadow effect from Button B ?