If you no longer want to associate a custom domain from a third-party provider with your Shopify store, then you can remove it from your Shopify admin, or transfer it to another Shopify store or domain provider. You can also remove subdomains.
.myshopify.com domain name can't be removed or transferred because you use your original
.myshopify.com domain name to log in to your Shopify admin and identify your account when you contact Shopify Support.
You can change your
.myshopify.com domain name once. However, you still need to use your original
.myshopify.com domain name to log in to your Shopify admin and to contact Shopify Support.
If you want to emphasize your brand by changing the domain that customers use to visit your store, then you can add a custom domain and set it as your primary domain. When you use a custom domain name, your customers don't see your
.myshopify.com domain name.