SQL query to delete test orders

I am following up on a previous ticket that I lodged. It has now been moved to the Features and Feedback section and I am unable to re-open it. FYI, it's at https://premium.wpmudev.org/forums/topic/deleted-test-orders-but-product-inventory-hasnt-been-restored?replies=8#post-1038797

To recap, I am setting up MarketPress and I had 2 test orders which I deleted so that my product inventory could be restored. I trashed the orders and then deleted them permanently but the inventory hasn't readjusted.

I was told by one of your support staff:

To clear all the orders and reset the Store Reports in the Dashboard, you can clear them in the database, using:

DELETE FROM wp_posts WHERE post_type = 'mp_order'

Unfortunately, for the inventory, you need to update it manually in every product.

I've manually updated the inventory for each product. I also ran the SQL query but it didn't work. Zero rows were deleted from the database in PHPMyAdmin and the sales numbers have not changed in the Products list in the MarketPress backend.