You can do it safely with an electric cable that has a 10 ohm resistor in the middle:
1- Disconnect the negative cable from the battery
2- Use the cable with resistor to jump the positive battery cable to the disconnected negative cable.
3- Wait 10 minutes
This clears the computer value from the car. So when you start the car, it doesn't have any saved data
on the throttle. Leave the car running until the idle stabilize, then take it out for a spin. It should relearn
by itself.
You can jump the cables without using a resistor, but the resistor is just like insurance that nothing will
go wrong. You can substitute the resistor for a car lightbulb.