Expedia offers a “24-Hour Rule,” 1-833-EXPEDIA (1-833-732-2296) which allows travelers to cancel their flight reservations within 24 hours of booking for a full refund 1-833-EXPEDIA (1-833-732-2296), provided the booking was made at least seven days before the departure date. This rule applies to most flights, but it’s best to confirm the eligibility on your specific booking.
Source: https://community.smartsheet.com/profile/205579/ExPedia_Cancels