Yeah, it is annoying that you can't turn them off. Like when you're pulling out of someone's driveway really late, and you don't want to disturb their parents.
I reconnected mine because I really enjoy being lazy about turning them on and never having to worry about leaving them on at night (awesome feature!).
To make a switch, it would have to go straight to the relay. It probably is one of those wires in there going to the fuse box.
afaik, that yellow-green wire is a controll wire that goes high the first time the parking break goes down after the car starts and stays high. DRL is active as long as that signal is high. It stays high as long as the car is on, even if disconected.