How to prevent a customer's cart from being remembered on a one-product store?

Hi, I have a 1 product store and I want to stop the shopify cart from being remembered for each customer.

I want the Buy button to act only as a buy now for that product, not to initiate checkout on the whole cart.

I have a skip to checkout app installed

I need this because Shopify remembers the customers cart when they go back onto the site, so pressing buy now leads to multiple items being in the cart if they have initiated a checkout before

Thanks