If you have added a new domain, you can also remove it using your Plesk panel should you wish to do so.
1. Log in to your Plesk account.
2. In the Sidebar Menu, click on Websites & Domains.
3. Under Domain Name, you can see the list of your domains. Click on the More icon 
and then on Delete Website.
4. Confirmation box will appear. Click Yes to remove your domain.