To edit a specific shipping rate or rates, you need to navigate to it in your dashboard, as described in the Rates and Destinations page.
Once you've navigated to the right place, you will see a screen like the following:
The By Itself and With Another values specify how much shipping charges you want to collect from your customers when they buy products in this shipping profile. The first product is charged at the By Itself rate, and subsequent products are charged the With Another rate. You can read more about how these rates work in the How Shipping is Calculated handbook page.
If you check the Enable Shipping box for a country or group of countries, then customers can select that country as a destination in the checkout form.
If you uncheck the Enable Shipping box, then products in this profile cannot be shipped to that country.
So long as a country is enabled in at least one shipping profile, it will appear as an option in the shopping cart checkout page. Be sure to make appropriate edits to all shipping profiles if you want to stop offering shipping to a specific country.
Simple Shipping for Canadian Provinces
When editing the shipping for Canada, you can apply different shipping costs for certain provinces. Under the regular shipping details, click "Canadian Provinces" to edit the shipping costs per province.