How do I remove my credit card from the saved payment option?

How do I remove my credit card from the saved payment option?  This is a shared account for our school-I do not want to keep my personal credit card attached to this account.

Since you have made payment via credit card, by default, only the last 4 digits of the credit card number will be shown in your Account settings.

If you do not want this option, you can change your payment method to PayPal. You need to cancel your subscription if you want to switch your payment method to PayPal and if you want to remove the credit card linked to the account. After that, you can upgrade your account.

Related guides for reference: 

How-to-Cancel-a-Subscription-and-Downgrade-Back-to-Free 

How-to-Upgrade-My-Account