square.onCustomerCustomAttributeOwnedDeleted subscribes to customer.custom_attribute.owned.deleted for the selected seller. It requires CUSTOMERS_READ.
Example
automations/square-on-customer-custom-attribute-owned-deleted.automation.ts
Event
A custom attribute owned by your application was deleted from a customer profile. This event replaces the deprecated customer.custom_attribute.deleted event. The signal resolves to the officialSquare.CustomerCustomAttributeOwnedDeletedEvent payload with type narrowed to customer.custom_attribute.owned.deleted.