Water shut off valve for water heater

[Cougar Campers]

I have a 2013 Cougar 333mks. Need information on how to turn off the water shut off valve for the water heater. It looks like you push it rather than turn. Can this be possible or am I missing something. Help please.

[hankpage]

Are you talking about the bypass valve on the vertical PEX tubing behind the water heater???? That is 1/4 turn from open to bypass. That is the only valve I know of to stop water from entering the heater.