Originally Posted by pandaperth

This makes sense to me.
To cancel earlier than after the 7th segment has been flown would result in an invalid RTW itinerary (since it is no longer round-the-world).
Cancelling after the 7th segment has been flown is a simple cancellation of all remaining segments.

I expect any refund after cancelling would be very small.
So the easiest option is just to no-show for segment 8.