why cant i just remove my card from a 1 week free trial and it just says that i need to add another card to remove my card i currently have? i should just be able to remove my card.
a valid form of payment is required when signing up for Stadia Pro or the Stadia Pro free trial as in your case (see here the terms and conditions). You will not be charged until the free trial ends, but the card is required. You can cancel at any time and after the free trial you can also remove your payment method as well, if it's still saved, e.g. in pay.google.com.