What is rules for JAL cancellation policy?

If i want to cancel my japan flights then what is the cancellation policy and rules?

The rules depend on the fare! Read them carefully.

And cheaper tickets tend to have stricter cancellation policies, not only in JAL but also in any other airlines.

You need to check the ticket rules - they are not all the same. Many people mistakenly believe that all tickets cost the same for the same type of seat and have the same rules - they don't. Basically cheaper tickets have more restrictions, with higher penalties - and you may be able to refund it with a penalty, or not be able to refund it at all.
If you bought the ticket from a travel agency, you must contact the agency - and do not let them foist you on the airlines. If you bought the ticket from JAL directly, then call JAL. In either case, have the reservation cancelled before the departure date and do not no-show the flight. In many cases, that's the kiss of death as far as getting a refund goes.
But here is a little secret the agencies and airlines do not tell you - even if you can't get any of the airfare back, you can still recover the taxes paid on the ticket - which could be nearly a hundred dollars, depending on the route. You may need to call them up and get pushy, but that is something you can get refunded - most airlines never tell you this and just pocket the money.