You are only able to request a trade cancellation if you and the other trader mutually agree to cancel the trade prior to any shoes being shipped out.
Please submit a request to our support team before your 72-hour shipping window ends and provide the proper documentation and/or screenshots of the mutual agreement to cancel within your request as well.
If your cancellation is approved, neither trader will need to ship out their shoes.
As much as we try to assist with all cancelation requests, we are not able to cancel a trade if one or both members have already shipped.