Where is the emergency fuel shut off switch on a 1987 Honda Prelude?

There isn't a readily accessible, single "emergency fuel shut-off switch" on a 1987 Honda Prelude like you might find in some other vehicles. Honda didn't typically include such a switch as standard equipment in that era. The best way to stop fuel flow in an emergency would be to disconnect the fuel pump's electrical connection at the pump itself (requires some mechanical knowledge and access under the vehicle) or disconnect the fuel lines at the fuel rail (even more involved and potentially messy). These are not ideal solutions and should only be attempted if you know what you're doing, otherwise professional help is advised.