To mark the item as dispatched open the original Simple Delivery label.
Then change the tracking number via View Order Details > Postage > Track Package > dropdown arrow > Add Tracking. That has to be done on a desktop browser. Even without doing that the payment will be released after 14 days.
If the buyer paid for the original label the cost will be automatically refunded to them in 30 days.
You can opt out of using Evri here:
https://www.ebay.co.uk/ship/prf
@djangosy