Tom
Hi Tom,
What do you mean by “ currently on the most basic membership” ? As far as I know, if you have cards, you are on the premium membership. In this membership the cards are included. Even if you cancel them all, the membership (and therefore the fee) won’t change. You can’t go back to the free membership with one IBAN and no cards. This is no longer possible.
You could downgrade to the travel card membership, but then you will have only that: a travel card. This means no IBAN accounts, so no online banking.
The only change that would make it cheaper, is to join a pack or to change to joint accounts to share the costs.
Simply cancelling the cards won’t change the costs I’m afraid.