You may sometimes have to edit customer details in order to complete aspects of the order fulfillment process. In these cases, you can change any detail of the customer's record:
Go to the Customers app.
Locate the customer in the list and select it.
Select any value and edit as necessary.
Your customer is now updated. You can also see if the customer is subscribed to your mailing list:
To remove the customer from your mailing list, uncheck Customer accepts marketing and save.
To delete a customer, return to the customer list and check the box next to the customer you wish to remove. Click the trash can icon, then press Remove in the confirmation dialog box.