Feel free to disable/ remove the expression link. The rest we can't know, anyway. Nobody on this planet can know each and every template that's being sold out there. Since this is basic stuff, I recommend you start by reading the online help.
The color you are trying to change is controlled by the Colorama effect. It could be on another layer. You can open up the Flow Chart and look for Colorama, or try searching the timeline for Colorama and change it there. You can also expand the expression and discover the link to the Colorama effect, open that layer and change the color there.
The easiest way to figure out what is going on with a template is to open the Composition Flowchart for the main or master comp and expand every layer. This will show you every nested comp, every layer, and every applied effect.