How to expose only off command to Alexa

Using cloud component and alexa.

What would be a good way to have command “Alexa, turn off all lights” and not to have turn on all lights command working?

I have “All lights” group exposed to Alexa.

create an input_boolean
create an automation that turns off all lights and that turns on the input_boolean after that.
expose the input_boolean to alexa as all lights.

now you can turn off the boolean and it will turn out all lights, but the input_boolean will always be on, so you cant turn it on with alexa.