remove Calculator interface

src/main/java/com/ap/BasicCalculator.java

@@ -15,9 +15,4 @@ public class BasicCalculator implements Calculator {
     public int product(int a, int b) {
         return a * b;
     }
-
-    @Override
-    public double calculateArea(double a, double b) {
-        return a * b;
-    }
 }

src/main/java/com/ap/Calculator.java

@@ -1,8 +0,0 @@
-package com.ap;
-
-public interface Calculator {
-    int add(int a, int b);
-    int subtract(int a, int b);
-    int product(int a, int b);
-    double calculateArea(double a, double b);
-}