square.onOrderCustomAttributeOwnedDeleted subscribes to order.custom_attribute.owned.deleted for the selected seller. It requires ORDERS_READ.
Example
automations/square-on-order-custom-attribute-owned-deleted.automation.ts
Event
A custom attribute owned by your application was deleted from an order. The signal resolves to the officialSquare.OrderCustomAttributeOwnedDeletedEvent payload with type narrowed to order.custom_attribute.owned.deleted.