To cancel a preapproval set up in Paypal you can contact the product owner or you can cancel your payments by going to your Paypal account directly.
If you are logged into your Paypal account you can click the following link to go directly to your list of Preapprovals: https://www.paypal.com/us/cgi-bin/webscr?cmd=_ap-manage-preapprovals
Or you can follow the steps below to cancel your subscriptions. Start by going to your account Settings, then to subscriptions. 
Select My Money on the Settings page.
Select My Money to see the link to your preapproved payments.
Select Update and you will be taken to a list of subscriptions. At the top of the page you will see another link to your preapprovals.
Clicking the preapproved payment plans will bring you to the list of Preapprovals you have in your Paypal account. The direct link to the preapproval page is: https://www.paypal.com/us/cgi-bin/webscr?cmd=_ap-manage-preapprovals
Select the Preapproval you wish to cancel and select Cancel.
