How do I turn off the results from lesson one: make the car move

I'm just getting started (very green). I completed lesson one, turned on the battery power, and car moved. Yeah! Now I'm starting on lesson two and got to the step of turning the power on in order to link with blue tooth on my iPhone, and car won't stop moving. Help!
I'm working on the Smart V3.0 Robot Car Kit.

Lesson one of what?

Lesson 1 of the Elgeoo Smart V3.0 Robot Car Kit.

Disconnect all pins from your Arduino and upload the sketch you want.
Then connect your Arduino back into the system and power it up.

Thanks!

Or do File/New in the IDE and upload the blank sketch until you are ready to upload another one.