I hope you are looking for to remove the blue default ListBox selection. That color is coming from the IsSelected DataTrigger on the ListBoxItem style. You can override that by creating a copy of ListBoxItemStyle, which is ListBox.ItemContainerStyle
Just a little more inside information about a ListBox customization. Basically a ListBox customization includes overriding below styles and templates
- ListBox.Style - if you want to change the Way the outer shell looks and feel
- ListBox.ItemTemplate - Set the appropriate DataTemplate to display the Individual properties of a type T, where ListBox.ItemsSource is bind to IEnumerable
- ListBox.ItemsPanel - Set the ItemsPanelTemplate which contains a Panel so that the items get laid out by the panel. By default it is a StackPanel with orientation is vertical.
- ListBox.ItemContainerStyle - set the style of the ListBoxItem