In Magento, refunds are handled through Credit Memos. You can only create a Credit Memo after an invoice has been generated for the order (For guidance on generating an invoice, please click here). Here’s a step-by-step guide to issuing a partial refund using the Magento 2 admin panel:
Step 1: Go to Orders
Step 2: Find the Order
Step 3: Open the Invoice
Step 4: Create a Credit Memo
Step 5: Adjust the Refund Amount
You cannot refund more shipping than what the customer originally paid.
You cannot refund more than the total amount originally paid by the customer.
Step 6: Process the Refund