You must have purchased this label using Custom Postage as Simple Delivery does not have Yodel as a postal option..... yet !
You can receive a full refund for the unused label here, you may need to wait 24 hours for the label to appear, before being able to void it.
Find your label with this link . https://www.ebay.co.uk/ship/lmng/labels-history/seller-hub and to the left of the sales record there is a drop down menu under 'Actions' click on that , then click on 'Void Label'.
The refund will take between 5 - 21 days to process.
@ivonka_s2010