You can delete a subset of orders from your import by going to the Import Log page.  To get to the import log page, click the View Import Log button to the right of the Import Data heading on the import review page.

This will bring you to a list of orders that have been processed.  The import log will display the Shopify Order Number, the orders status, and a message indicating if the order has been imported, deleted, or has an error.  There's a check box to the left of the order which is enabled for orders that are marked imported.  If the order was deleted, the check box will be disabled  If the order is marked an error it'll have N/A as the Shopify Order Number.

To delete individual orders, click the checkbox to the left of the order.  You can select multiple orders at once and can delete up to 500 orders at a time.  Once you've selected your orders, click the red Delete Selected Orders button on the top right of the page.

When orders are successfully deleted, the credits used to import the orders will be added back to your credit bank just like when deleting your entire import.

Partially Deleting Your Import

If you delete a subset of your orders and realize you need to delete the entire order you can still do so.  Simply click the Delete Imported Orders button on the bottom of the review import page as you normally would.  Any orders that have already been deleted will be skipped and the rest of your orders will be deleted.

It's still best to delete your entire import if you need to delete the majority or all of the orders that you've imported.  Deleting individual orders is best if you only need to delete a subset from the import.

The same rules apply when deleting a subset of your orders or your entire import.  You should read over the delete import article to fully understand what orders can be deleted and how configuration options are affected when deleting orders.