Freya here with the Shopify Support Team :)
If you're using Shopify to track inventory an item will always be deducted when an order is paid for to prevent selling out of stock items. However, you don't have to use Shopify to track inventory! If need be you can use another inventory management software and integrate it with your Shopify account using an app. Take a look through the available inventory management apps, to see if there's one there to meet your needs!
I hope this helps!