You can cancel a subscription up to the day of the next scheduled payment. 

If you want to cancel a subscription, please follow these steps:

•Log in to your PayPal account. 
•Click History at the top of the page. 
•Find the subscription in your History. 
•Click the Details link for the subscription. 
•Click the Cancel Subscription button. 

Please note that this is just for your reference, please always follow the instructions in PayPal for the latest updates on this process.