You can delete a custom domain from your Looker (Google Cloud core) instance if, for example, the domain is no longer in use or you need to reconfigure it. Deleting a custom domain reverts your instance URL to the default domain assigned at creation.

Follow these steps to delete the custom domain of your Looker (Google Cloud core) instance:

1. On the **Instances** page, click the name of the instance for which you would like to remove the custom domain.
2. Select the **CUSTOM DOMAIN** tab.
3. Select the **Delete** trash icon next in the domain mapping.
4. In the deletion dialog, type "delete" into the text field and select **CONFIRM**.

Once the domain mapping is deleted, you will be directed to the **Instances** page in the Google Cloud console. The **Instance URL** on the page will revert the default domain that was assigned when the Looker (Google Cloud core) instance was created.