unfortunately you can't because the point of the game is to get all the cars so you can race them in the same manufacturer races.
Chat with our AI personalities
warehouse
make sure you are in another car and then select the car you want to sell from the my cars tab and click sell, or if you are feeling lucky, throw it in the auction house for retail price and see if some person will buy it!
Zabaglione, Zenith cameras, Zephyr cars, Zodiac cars just to name a few.
You need to go to the sandpit at your estate and walk up to the wheelbarrel to sell your flowers.
all you need to do is do quests and sell items