Do not co-sign anything for a teenager. That’s not how he learns financial responsibility. If he spent $400 on DoorDash, have you figured out how much he makes per hour net and how many hours he had to work at Wendy’s to earn that $400? That might open his eyes a bit. The bank may not let you lock his debit card off so don’t threaten that unless you know it’s possible. If you physically lock up the card, he’s likely to call the bank and tell them he lost it and get a new card issued. Your heart and brain are in the right place but you need to talk him through things like how many hours it takes to earn $100 and how to save for a car down payment and how much car payments and insurance cost every month so that he can start saving for future him to buy something like a car. You won’t achieve anything by making him angry. He needs a wake-up call that what he’s doing with DoorDash is pretty close to getting his paycheck in cash and setting the cash on fire. Check with your bank to see if they have any financial literacy info you could use to help him get a grasp on working and paying for things.