I tried to delete a product and got this error: 

The operation cannot be completed, probably due to the following:
- deletion: you may be trying to delete a record while other records still reference it- creation/update: a mandatory field is not correctly set
[object with reference: Quants - stock.quant]

So I tried to set the products stock level to zero, but then I get this error:

The operation cannot be completed, probably due to the following:
- deletion: you may be trying to delete a record while other records still reference it- creation/update: a mandatory field is not correctly set
[object with reference: Change Product Quantity - stock.change.product.qty]