At Tilda, we do not store this data on our servers—it remains saved only in the user's browser. To delete the data, users should clear the browser cache. Contact info is encrypted, so no attacker will be able to intercept it.
To enable this feature, go to block ST100 "Shopping cart with an order form" → Content → Input fields, and add "Checkbox: Save contact data for the next purchase."
Learn more: https://help.tilda.cc/online-store-payments/cart#autofill