Hi,
There is no standard functionality in Dynamics 365 Finance & Operations to bulk cancel multiple purchase orders. When multiple POs are selected from the All purchase orders page, the Cancel button is disabled by design. If this is a business requirement, it would require a customization.
While you could export and re-import purchase orders using a data entity with the status changed, this approach is not recommended, as purchase order status is controlled by business logic and validations, which can result in errors depending on the order state.
