LL - How to turn off auto fill info in the shopify cart

If the Shopify cart is automatically filling in a customer's contact and payment information during checkout,  the customer must have opted into Shop Pay. Shop pay is an app (like Apple Pay) that stores your credit card info, and auto-fills it when you are placing an order. Unlike Apple Pay which can be used at different locations, Shop Pay is specific to Shopify stores.

They can opt out of Shop Pay at any time by visiting this page