24 hours to void Amazon-partnered carrier charges and get a full refund

Hi all
Where do I find this in the new workflow ?
It was so easy to void UPS charges in the old workflow but as normal it always has to be difficult.
I’m selling everything off at cost price so I need to void any UPS shipping costs
Thanks in advance for any help x
Stated in the new work flow
(Small parcel shipments: After you have confirmed your shipping selections and accepted the charges, you have 24 hours to void Amazon-partnered carrier charges and get a full refund.)