feat(remove-item): handle 'removeItem' method

src/methods/remove-item.js

@@ -0,0 +1,32 @@
+export default (self, itemId, save = true) => {
+  // find respective item on list by ID
+  const { cart } = self
+  for (let i = 0; i < cart.items.length; i++) {
+    const item = cart.items[i]
+    if (item._id === itemId) {
+      // item found
+      // remove from items array
+      cart.items.splice(i, 1)
+      cart.save()
+      return item
+    }
+  }
+  return null
+}
+
+/**
+ * @method
+ * @name EcomCart#removeItem
+ * @description Remove specific item from cart by ID.
+ *
+ * @param {string} itemId - The unique object ID of item
+ * @param {boolean} [save=true] - Save cart data
+ *
+ * @returns {object|null} Returns the removed item object or null
+ * when item not found.
+ *
+ * @example
+
+cart.removeItem('12300000000000000000000f')
+
+ */