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 kind of encryption does LiquidVPN use?
LiquidVPN implements the highest level of encryption natively supported by each of our VPN...
Do you limit users data usage or bandwidth available?
No, LiquidVPN will never impose bandwidth restrictions or data caps on a user. In fact we...
Do you provide OpenVPN configuration files for 3rd party VPN clients?
Yes. We provide OpenVPN configuration files for many different operating systems. You can...
How fast are your VPN servers?
LiquidVPN only runs dedicated baremetal servers with 1 Gbps or 10 Gbps ports. We only use premium...
Do you offer a guarantee?
Yes, we offer a money back guarantee. If for any reason you are not happy with LiquidVPN cancel...