Removing subdomains
When you remove a subdomain from your store, it might impact how your store is set up or how your customers find your store. You can't remove a subdomain that's your primary domain.
Before you remove the subdomain, verify that it isn't being used in your store to find certain pages, and that it's not the primary domain.
Steps:
Desktop
From your Shopify admin, go to Settings > Domains.
Click the subdomain that you want remove.
Click Delete subdomain.
In the dialog, click Remove to confirm.
Mobile
From the Shopify app, tap
, and then tap
Settings.
In the Store settings section, tap Domains.
For the subdomain that you want remove, tap Actions > Delete subdomain.
Tap Remove.