You can cancel a subscription up until the day of the next scheduled payment. Remember, this cancels all future scheduled payments for that subscription.
 
Here's how to do it:

1.  Log in to your PayPal account.
2.  Click History under My Account at the top of the page.
3.  Choose Subscriptions from the Show drop-down menu.
4.  Check the From box and change the date back to the year the subscription was created.
5.  Click Search, and then click Details.
6.  Click Cancel Subscription.
7.  Click Cancel Subscription again.