To cancel your subscription click the VPN Administration button on the left hand menu of https://my.liquidvpn.com/clientarea.php 
Click VPN Administration 
Click the service you want to cancel
Click Request Cancellation
Choose to cancel immediately (takes up to 24 hours to process) or at the end of billing period
Either option will stop your subscription before being billed again.

Also Read

What methods of payment does LiquidVPN accept?
We accept the following currenciesPaypal, Credit Cards, Cash, Bitcoin, Litecoin, Peercoin,...
Are there any hardware requirements to use LiquidVPN?
A VPN client will run on virtually any semi modern device. It should be noted that the CPU power...
Can I use LiquidVPN on a mobile device?
The short answer is yes However we have not released our mobile VPN client yet so you will need...
Can I use Bittorrent and P2P?
Yes, LiquidVPN fully supports bittorrent and P2P on all of our servers. We will never censor P2P...
Do you offer a guarantee?
Yes, we offer a money back guarantee. If for any reason you are not happy with LiquidVPN cancel...