Your customers should be able to unsubscribe to promotional emails by clicking on the Unsubscribe button within the email they received. However, if they are unable to do so and they have give you consent to remove them from the mailing list, follow the steps below:
Head to Communication tab
Click Unsubscribe an email
Fill in the customer's email address and click Save Changes
How To View Unsubscribed Emails
On the Communication page, click the '+' button, then click Unsubscribed
You will see a list of unsubscribed customer email addresses and when they unsubscribed
Even if an email address has been unsubscribed, it will still receive emails that are deemed important such as:
Outstanding or overdue invoices
Statements