If you remove the load control module and wire nut the incoming and outgoing 240VAC wires together (L1 and L2 separate of cource), and place a cover on the junction box, it will be like a standard install. You'll have to terminate the 120VAC line coming into the box, or remove it.
The water heater is usually hard wired directly to a circuit breaker, no switch in line.
There may be a service disconnect near the water heater if the circuit breaker panel is not near by.