You can decide to turn off the subdomain of your knowledge base and make it accessible only when accessed through a certain place on your website or web app where you have it embedded. For example, hidden behind your own authentication. Here's how to turn of access to your knowledge base unless accessed through the JS embedding.
Navigate to the Settings page of your help center and after the "Visibility" option in the "General Settings" widget, turn the "Make it accessible only via JS" option on, then click on the "Save" button to confirm your change.
You can also allow only certain domain names to display your help center by adding them in the field that appears below the JS-only toggle.
Now, if you try to open your knowledge base at the subdomain you created, it will display a 403-status code rendering it unavailable unless it is accessed through the JS embedding. There's how you can embed your knowledge base with JS.