How best to pull out of an Amazon regional marketplace?

We’re a US based company that recently started to sell in the Canadian and UK marketplaces, including shipping small amounts of inventory to warehouses in both countries. The experiment appears to be a failure at this point, as it is barely profitable and too time consuming dealing with quarterly VAT tax submissions, international shipping, and such.

So, we’re trying to figure out what our options are to deal with our inventory in these countries and close the accounts. I’m assuming our options are to either ship all inventory back to the United States or have Amazon destroy the inventory?

We’ve reached out to Amazon Seller support, but they’ve been completely unhelpful so far.

Has anyone dealt with this situation before? Any guides out there? Any help is much appreciated.