Hard-delete a discount. Only a discount that has NOT been applied to an order can be deleted; a used discount returns 422 (expire it with expired: true instead, to preserve its order history).

A discount enters that state through an applied-discount record, written when a buyer redeems the code at checkout or when a ClickFunnels user applies it in the admin UI. A code an integration created and never published carries none of those records, so it is always deletable.