If you're looking for a fuel pump cutoff, you would need to check:
* Under the hood: Look around the fuse box and relay area. An aftermarket switch might be mounted there.
* In the cabin: Some people install them near the driver's side or under the dash. This is less common but possible.
* Wiring diagram: Consult a wiring diagram for your specific 1998 Chevy S10 to see if any such switch is wired into the system, although it's unlikely.
If you can't find a switch, the fuel pump is controlled primarily by the vehicle's computer system and safety interlocks. Turning the ignition off is the primary way to cut off the fuel pump's power.