When someone signs up to the newsletter, a customer account record is created in Shopify. The customer record will be tagged with “newsletter” so it’s easy to identify where they came from.
You can then easily export your customers and import them into your chosen newsletter service (e.g. Mailchimp).
If you want to hide the newsletter box, click “Customize theme” and click the “Sidebar” section then scroll down to the “Newsletter form” heading. Don’t forget to save your changes.