You can cancel your subscription at anytime, by logging into your account. Note, you need to be on Desktop, or the mobile version of desktop, to access this functionality.
Select 'My Account' from the main menu drop down, under your name. Select 'Manage or Change your Subscription' (an option under Subscription), click on the 'Cancel Subscription' link at the bottom of the screen and follow the steps to cancel your subscription.
You will continue to have access to the streaming service until the end of your current billing period, at which point your account will be cancelled automatically.
Free Trial: If you cancel within the 1 month free trial, you can continue to access the service until the end of the trial period.
Should you wish to renew your subscription at a later date, you can use the same account credentials if you wish.
If you signed up using your iTunes account, please click here for instructions on how to cancel your subscription.