See this page for tutorial
If you want to cancel your subscription you can go to this page:
And follow the instructions.
After you click on one of the Unsubscribe buttons
You will be redirected to the PayPal login page
After you log in you will see a list of active occurring payments and have the choice to stop them.
NB! If you do not cancel your subscription this way the payments will continue even if you uninstall the program.