This means that it's been attached to a price list I believe and needs to be deleted from that PL. All records (BOMs/Routings/Product Sites/Suppliers/Customers and Price lists) have to be deleted before can delete the product. Now depending on how long the product has been in the system and if you have MPS turn on, it may have to be run as well. Hope this helps

Thanks for the info, Charity

Unfortunately, there weren't any associated price lists and I've made sure to delete from everywhere you mentioned above. Any other ideas?

I am not sure where to find this as I don't access this area, but it's a Table in X3

Module Comma Data Table

That table is for costing records. Since you have cost against it, this product most likely has been used which means you cannot delete the items. Once the item is used it is very hard to get rid of or impossible. Your best option is just to make the item obsolete. I have asked many times over the years for a way to delete an item but since the database is a relational database, there are links all over the place that would need to be removed.