Is it possible to hide the region/province/state selector?

Shipping Rates Calculator+ gathers the shipping rates directly from the Shopify Cart API described at

This API requires three fields, country, state, and zip code, depending on the territorial subdivisions.

For that reason, we cannot remove any of the three elements for the form, as they are all mandatory. 

Anyway, that should not affect most of your customers, as their location will be populated automatically by our geolocation service.