You can cancel your subscription through your PayPal Profile. Here's how
   1. Go to the PayPal website and log in to your account.
   2. Click "Profile" at the top of the page.
   3. Select "Pay List" under the Financial Information column.
   4. Click on the subscription you would like to cancel.
   5. Click the "Cancel" link next to Status.
   6. Click "Yes" to confirm cancel.
Your status will change to "Cancelled." Additional subscription payments
will not be taken from your PayPal account unless you renew or start a
new subscription with a seller or service.
Here's more information:
    * You must cancel the subscription at least one day before the
scheduled date of the next payment to avoid a charge.
    * If you cancel a subscription on the day of a scheduled payment,
the payment might still be sent.

If the steps above do not work for you, you can cancel your subscription
through your PayPal history log. Here's how:
   1. Go to the PayPal website and log in to your account.
   2. Click "History" at the top of the page.
   3. Select "Subscriptions" from the Show menu.
   4. Check the "From" box, then change the date to when your
subscription started.
   5. Click "Search."
   6. Click "Details" on the subscription you want to cancel. Be sure to
click the transaction titled "Subscription Creation" and not a payment
transaction.
   7. Click "Cancel Subscription."