If you have ever had to cancel a USPS shipping label that you have created using ebay or paypal shipping you probably have been as frustrated as I when, for one reason or another, you need to cancel it and get a refund. Sitting for more than an hour searching ebay I finally fount the quickest way possible, and it isn't even on ebay. As you know, when you create a label on ebay or paypal, you receive an email saying that you have created a shipping label on ebay or paypal shipping. To cancel this label simply open the email, scroll down toward the bottom of the email and there will be a paragraph that will provide the exact link to cancel the very label you want to cancel.
You can also cancel the label on the Paypal page when you fisnih the label, but like me, you may make a mistake and not notice it till that page is gone.
Hope this helps someone as much as it did me.