Can I cancel my order?

There is no cancel button on an order. Message the seller right away: a seller can refund an order in full at any point, and before the package is scanned that works exactly like a cancellation.

Once the carrier has scanned the package it is on its way — from there, a problem with what arrives is handled through Buyer Protection, not cancellation.

If the seller never ships at all, you do not need to cancel: with no carrier scan within 14 days of the sale, the order refunds to you in full automatically.