As per the airline's official policy, you can cancel your specific fares, but there is no refund. However, the customers will get a future credit with the airline for future travel.
It can be applicable for a year from the date of issue. Moreover, you can connect with
JetBlue en español telefono in case you want to know more about the cancelation details from Spain.
How to cancel without paying the penalty?
According to the American Transportation department, the airlines must hold the reservations for 24 hrs without any charges. However, you can also cancel within the time limit.
Source:
https://cancellationflights.com/jetblue-telefono/
