Removed all the unused directives in the Solution with the assistance of Resharper

src/ApplicationCore/Entities/BuyerAggregate/Buyer.cs

@@ -1,6 +1,5 @@
 using Microsoft.eShopWeb.ApplicationCore.Interfaces;
 using Ardalis.GuardClauses;
-using Microsoft.eShopWeb.ApplicationCore.Entities;
 using System.Collections.Generic;
 
 namespace Microsoft.eShopWeb.ApplicationCore.Entities.BuyerAggregate

src/ApplicationCore/Entities/BuyerAggregate/PaymentMethod.cs

@@ -1,6 +1,4 @@
-using Microsoft.eShopWeb.ApplicationCore.Entities;
-
-namespace Microsoft.eShopWeb.ApplicationCore.Entities.BuyerAggregate
+namespace Microsoft.eShopWeb.ApplicationCore.Entities.BuyerAggregate
 {
     public class PaymentMethod : BaseEntity
     {