If you mean disable the selected item style, then in WPF you can do this:
<Style x:Key="NullSelectionStyle" TargetType="ListBoxItem">
<Style.Resources>
<!-- SelectedItem with focus -->
<SolidColorBrush x:Key="{x:Static SystemColors.HighlightBrushKey}" Color="Transparent" />
<!-- SelectedItem without focus -->
<SolidColorBrush x:Key="{x:Static SystemColors.ControlBrushKey}" Color="Transparent" />
<!-- SelectedItem text foreground -->
<SolidColorBrush x:Key="{x:Static SystemColors.HighlightTextBrushKey}" Color="{DynamicResource {x:Static SystemColors.ControlTextColorKey}}" />
</Style.Resources>
<Setter Property="FocusVisualStyle" Value="{x:Null}" />
</Style>
<ListBox ItemContainerStyle="{StaticResource NullSelectionStyle}" ...>
Unfortunately I don't have access to Windows 8 yet, so I can't say if it works on WinRT.
Alternatively if you don't need any selection at all, just use an ItemsControl.
For example, instead of <ListBox .../>
use <ItemsControl .../>
. An ItemsControl shows a list of items like a ListBox but has no concept of the selected item.