To refund any transaction for a customer, follow these steps:

1. Open the customer's profile.
2. Navigate to the billing and invoice section, as shown in the screenshots.

3. Access the payments section, as indicated in the screenshot.

4. Click on the "void" button, as highlighted in the screenshot.

Now, you have two options for the refund:

For a full refund:
5. Choose the refund type as "full" and proceed.

For a partial refund:
5. Select the refund type as "partial" and enter the specific amount you wish to refund.

Additionally, if you'd like to transfer the refunded amount to the customer's credit card:

Click "yes," and the amount will be transferred to the customer's credit card. You will receive a confirmation message.

If you do not wish to transfer the refund amount to the customer's credit card:

Click "no."

Following these steps, you can successfully refund any transaction of a customer.