Currently this is not an option via our API with eBay. We've been adding this function on a store by store basis and you can see which platforms current support this function here. While our Product Team does not have plans on the immediate horizon to add this for eBay, you may be able to move it up the list by posting to our existing Community Forum thread:
In the meantime, we have a couple of options: Mark as Shipped or Clear Orders.
Mark as Shipped: retain a record of the shipment in ShippingEasy and move your orders to your Shipment History without purchasing a label. For more information, take a look at how to mark an order as shipped.
Clear Orders: completely remove the order from ShippingEasy. For more information, take a look at how to delete an order.
I hope this helps!