You can delete a server in the Control Panel. After deleting it will disappear from the list of servers, all data will be erased from it, and the payment will no longer be charged.
Open the tab with your servers. Click on the one you need and click on Delete button. After clicking you will see a confirmation window. Click on Ok if you want to delete your server, click on Cancel if you do not.
Please note: after deletion, there is no way to restore the server!
After clicking on Ok your server will be automatically deleted.