There are two ways to cancel Oberlo: uninstall Oberlo or close down the Shopify store.
Go to Shopify admin > Apps page and click the garbage can to delete the app.
Closing Down the Shopify Store
If you decided to stop running the e-commerce business, you can directly close your Shopify store. By doing this, the Oberlo subscription will be cancelled automatically.
Resubscribing Back to Oberlo
If you change your mind later on, you can always resubscribe to Oberlo. Just install Oberlo, and all products will be synced back.