The system has been designed as such that supplier price lists cannot be deleted from the supplier's account.
The reason for this is that is causes a lot of issues where there are active products within the price list, it also causes issues with product history for customers as well as in price comparison.
If you have a price list for a customer you no longer trade with, please see this guide on deactivating a price list.
Supplier no longer able to delete price list
Supplier is no longer able to delete price lists.
Written by Cristian Bolba