If you decide Digital Downloads Pro is not for you, you can uninstall it at any time by doing the following:
In your Shopify Admin, go to the Settings section
Find the "Apps and sales channels" section.
Locate Digital Downloads Pro in your list of installed apps
Click the Uninstall link all the way on the right side and confirm.
This will automatically remove the app from your Shopify Admin, cancel your subscription, and stop all recurring charges.