Major airlines are letting customers change — and even cancel — flights traveling to or from the New York metropolitan area as the city prepares for severe storms this week. American AirlinesAmerican Airlines said it is waiving the fee to change certain flights traveling into or out of both JFK and LaGuardia airports on Tuesday. The airline is letting travelers make one-time changes for flights booked as recently as Sunday, so long as the trip’s origin and destination don’t change. The exemption applies to those who booked JetBlue flights traveling to or from JFK, LaGuardia and Newark airports from Monday to Wednesday, according to the advisory. Delta AirlinesDelta is letting travelers traveling to or from airports in New York City, New Jersey and White Plains make last-minute changes without incurring fees, the airline confirmed.