Where is the fuel cut off switch on 1994 fiesta xr2i?

There's no single, universally located fuel cut-off switch on a 1994 Ford Fiesta XR2i like you might find on some other vehicles. Ford didn't typically include such a switch as standard equipment on that model. The only way to reliably cut fuel supply would be to disconnect the fuel pump's electrical connection or the fuel line itself. This requires mechanical work under the car or in the engine bay. Remember that disconnecting fuel lines requires care to avoid spills and potential fire hazards.