Error 8018

Cannot delete a non-existing relationship for SKU [%s].  For full details, see http://sellercentral.amazon.co.uk/gp/help/23861

This error occurs when you use a relationships feed to delete a relationship that does not exist. To resolve this error, you should do the following:

1. Check the ParentSKU and SKU values in your relationships feed to ensure you entered the correct SKU.
2. If not, edit the incorrect SKU and post your relationships feed again.
3. If the SKUs are correct, you do not need to take further action. No relationship presently exists for the parent product and child product.