Disable Stripe email notifications from Commerce
You shouldn't need to adjust Craft Commerce at all. You can disable email receipts on the Stripe side in your account settings. 

Account Settings > Emails

Uncheck "Email Customers for: Successful Payments"



As far as Stripe using the previous email address saved with the Customer, as far as I know OmniPay (which powers Commerce) doesn't create a Customer in Stripe, it only creates a Charge.