Why do you want to turn those tracks off? Leaving them on does not hurt them. And, they lights can stay on.
Power Routed turnouts would easily resolve this. Nothing else needed except 2 wires to the track, to connect an LED.
To 'disconnect' the staging tracks, you will need to isolator joiners at the turnout. Then wire a DPST Toggle (or Slide) Switch to the track and also to your DCC. Make sure you keep the same polarity of the wiring. On the Track wired side, connect additional 2 wires to the Resistor and LED (polarity on these 2 wires not necessary as it is only an LED.? See attached.
Note the position of the Toggle switch !? It 'points' to the end contact it is connected to. (Solid outline position points to Staging track/LED). When you want the Staging track off, move the Toggle to the dashed outline position (points to 'no' contacts.
DPST are relatively popular but DPDT are generally more popular. Wire the same, just leaving the other 'end' terminals unused.
Slide switches make this more obvious, with the slide handle 'slid' over the connecting contacts.
Happy Ho-Ho's
Jeff
SF Bay Area Z
a.k.a. 'The BAZ BoyZ'