Were is fuel shut off switch for a 2004 explorer?

There isn't a readily accessible, manually operated fuel shut-off switch on a 2004 Ford Explorer like you might find on some older vehicles. The fuel system is controlled electronically. In the event of a crash, the fuel pump will be deactivated by the onboard safety systems. If you need to shut off the fuel supply for some reason (e.g., a major fuel leak), you'd need to disconnect the fuel pump's electrical connector or perhaps the fuel pump relay (which would require knowing the location of the relay in your particular vehicle's fuse box). However, working on the fuel system is dangerous and should only be done by someone qualified and experienced. Improper handling can result in fire or injury.