With all due respect, Kathleen, your reference to "cancelling a memberhip" was confusing.
What some "may not know" and what you did not explain is that HGVC is not a membership that one either joins or cancels, as if it were a AAA membership. Buying a TS is akin to buying a house or getting married. There is no "cancelling." You are in it for the long-haul. The only "refund" comes when you sell or get divorced... at that point, the settlement controls how much you "get back."
Edited to Add: ... If you are talking about an annual participation at an affiliate: Yes, you may join and elect to participate, and the activation fee is non-refundable, but its for an indefinite period of time (as long as you own the TS), so there is still nothing to be refunded.