To View Failed Imported Orders,

1. Goto Magento 2 admin panel.
2. On the left navigation bar, click the Rakuten FR Integration menu.
3. The menu appears as shown below:
   
4. Click on Failed Imported Orders.
   The Failed Orders page open as shown:
   
5. The failed orders with the reason will be shown.

To delete order,

1. Select the orders you want to delete.
2. Then click on the Delete Orders button on the top right side.
3. The selected orders will be deleted.