How do I make the change so that no more customers from some of the countries will be able to place orders from my website?
Importance:
In case you want to focus on a particular marketplace/ country only, and do not want to sell your products to other countries or do not wish to receive sales from other countries.
How to enable this?
This can be done via markets in Shopify.
The steps are:
Click on Settings under Shopify admin store
Click Markets: Here you as a merchant can enable the markets required or disable or leave other markets not needed orders from. So the markets which are not added, the customers from these countries would not be able to place orders/ cannot checkout.