I cannot process in the website because it requires a SkyPass account number. I do not have a KE FFP account. I have found from previous online bookings that it is not even possible to change seat selections unless you have a SkyPass membership number. It appears the KE website is very limited to non-SkyPass memebers.
Unless you know otherwise how to access the refund ability.
Create a Skypass account. Then add your reservation to it. And you will have ability to cancel through there. Well, you should have access after that.