Welcome to Shopify Community. My name is Olivia and I work here.
I appreciate your question, and I'd be glad to provide some insight on this for you today. We definitely don't want you to have to pay for a shipping label that will not be used! In fact, you can void your shipping label in just a few short clicks. Before you begin, make sure your label meets the following criteria:
If so, move forward with next steps.
From your Shopify admin, go to Orders.
Click the number of the order with the shipping label that you want to void.
In the Fulfilled section, click More > Void label.
Select a reason for voiding the label.
Click Void label and insurance to confirm.
Tip: You can buy a new label for this order should any changes happen.
I trust this will do the trick, but let me know if any other questions come up that I can assist with today.