How do I spawn a bunch of random stuff then randomly delete one and replace it with something else?

I'm making a parking simulator game, and I want to make it so the cars in the spots are randomly chosen to make individual levels more unique, then replace one spot with the goal so the player has to find the spot and successfully park to progress to the next level. How can I make this happen? There are 3 cars for obstacles, and for convenience's sake, they're all the same car with different colors.

You can use choose(1,2,3..) to pick a random number from a selection.

The number can apply to a car, once picked it spawns that car.

You can pick a random instance of a spot if it's an object and assign that goal=true, while the rest are false.