I have a Kodiak Cub. There is a valve in my Cub on the water heater in line. It is on the back side. Originally I had to remove a panel inside the front pass through to get at the valve. The panel was held in place by screws into the floor and walls.
The valve will be on the back side very close to the water inflow. I have seen systems with two valves as well. The second valve if you have one would be on the hot pipe out. It would be on the backside at the top.
I installed a hinged door so I didn't have to unscrew everything.
I wish you good luck and happy trails ahead!