All fields, except for System Fields (Date of Birth and Marketing Preference) can be deleted at any given time.
Important: Please note that deleting a field will not only delete the field but also all the customer data for associated to the field as well and it cannot be undone. So if you wish to keep the customer data already gathered but simply stop showing/asking future customers for it then please edit the field instead.
Deleting a Field
To delete a Field head to Settings >> Customer Fields >> click the "Details" button next to the relevant Field and click the "Delete" button:
On the next page, you'll see a confirmation page reminding you that the action cannot be undone and asking you to confirm that you're aware that "Any data stored in this field will be permanently removed from all customers". Simply tick the box and finally click on "Delete Field" button:
Once done the field deleted will no longer be displayed in your Customer Field page, customer profile page and/or any forms previously displayed.