Look at the attached screenshot. Are you talking about the 1st switch, or about the 2nd one?
The first is Emergency Disconnect Lever. Per -1: "Momentary
actuation of the lever immediately deactivates both the anti-skid
and SAS systems and the switches go to OFF." By default it is not mapped, but you can do it manually in Options->Controls.
The second switch is Nosewheel Steering Switch. In-flight it also controls the laser fire.