The owners manual says to put the manual transmission into 1st gear, release the parking brake, and turn the ignition OFF. Perhaps the switch the garage mentioned is the electronic parking brake switch. If that is left on, it will drain the battery. I don't know if the parking brake works on all the wheels, the front wheels only, or the rear wheels only. If it is the rear wheels, it wouldn't tow very well if at all.
The things you own control your life.
2021 Winnebago Vista 35U towing a 2022 Jeep Cherokee Trailhawk
2010 Cadillac SRX 2003 Itasca Sunova 30B