How to write a request letter of refunding insurance to insurance company

i was paying my insurance for the past years, but for now I am about to leave the country of Samoa for Australia Seasonal Working, but I check my insurance and it getting lower because the Insurance Company is taking the money, so I decided to refund my Insurance.

I went there and they me to made a request letter for them.

So i really need some help about this letter and how to write please