How do I cancel a flight?
As soon as you know you won’t make your flight, call the airline immediately and talk to their customer service. If you’re lucky, you’ll catch a representative having a great day who is super willing to help you out. Be polite, courteous, and gracious—a pleasant attitude can go a long way. First, ask for a refund.
https://s3.amazonaws.com/travel-support/Norwegian_Airlines_Live_Agent_New_Reservation_Flight.html
https://s3.amazonaws.com/travel-support/Norwegian_Airlines_Live_Agent_New_Reservation_Flight.html