How do you turn off the passenger side air bag on a 2000 ford Ranger?

You can't turn off the passenger-side airbag in a 2000 Ford Ranger using a switch like some newer vehicles have. There's no such feature on that model year. The airbag is always active unless it's malfunctioning (which would be indicated by a warning light).

Important Safety Note: Disabling the passenger-side airbag yourself through any modification is extremely dangerous and illegal. It's designed to protect occupants, and tampering with it could lead to serious injury or death in a collision.

If you have a specific reason you want the passenger-side airbag deactivated (e.g., you need to transport a child in a rear-facing car seat), you should consult your owner's manual for any recommendations or consult a qualified mechanic or car seat technician. They can advise on the safest way to transport children in your vehicle.