Where is the cut off switch for a 1986 Chevy s10?

The cutoff switch for a 1986 Chevy S10 isn't a standard factory feature. There's no single, universally located "kill switch." If a previous owner installed one, it could be virtually anywhere – under the dash, in the engine bay, or even hidden elsewhere. You'd need to visually inspect the vehicle to find it, or check any documentation the previous owner left behind.