If you are referring to the shopify URL like "myurl".myshopify.com, you may not be able to change that, however you can always change the shop name on front end
I'm Tira and I am here to help. Thanks @Propero for helping out. That's correct, once the myshopify.com URL has been registered, there isn't a way to change it. You can learn more about this in our help doc here: Managing your domain in Shopify.
You can change your store name if you prefer.
Here are the steps:
1) Login to your Shopify admin
2) Click on Settings > General
3) Under Store settings, you can type your desired name under the Store Name heading
4) Click Save
You can also check out these instructions in our help doc here: Adding business details to your store along with steps to adjust your store's currency, time zone and legal business and address.
Let us know if this helps you accomplish what you're looking to do.