final modify

최종 수정입니다.

backend/routes/transaction.js

@@ -50,7 +50,7 @@ router.post("/success", async (req, res) => {
   var userId = sess.userid;
 
   try {
-    await Transaction.remove(
+    await Transaction.deleteOne(
       {
         bookTitle: req_bookTitle,
         $or: [{ buyerId: userId }, { sellerId: userId }]