How to turn off hot water

Most have knobs on top of the sink that turns the water off and on.

Most have a valve under the sink that shuts the water off.

Most houses have vavles on the hot water heater that allows the water to be shut off

Most houses have a master water valve that will shut all the water off to the house.

And all houses ( except those with wells) will have a valve on the water meter. And those with wells you can turn the well off.

If water is turned off TO the water heater, turn the power off to it.

More important then turning the power off to the hot water heater is opening a hot water tap unless there is an expansion tank between the valve you closed and the tank. Water must always be free to flow in and out of it.

How to turn off hot water
To where? The entire house? This is done at the hot water heater. To a certain fixture? This is done in the cabinet at the hot water angle stop. Good luck, Tom