Expedia can take up to 24 hours to process your refund. Once that has happened, your bank or payment service (such as PayPal) will take care of the rest. Just know that it may take them up to 7 days to post the credit to your account, and up to 2 billing cycles to show the credit on your statement.
Source: https://www.devex.com/people/airdeals-does-expedia-allow-cancellations-2101060