There are a few important things to keep in mind when returning a product you purchased from the U.S. Apple Online Store:
You have 14 calendar days to return an item from the date you received it.
Only items that have been purchased directly from Apple, either through the Apple Online Store or at an Apple Retail Store, can be returned to Apple. Apple products purchased through other retailers must be returned in accordance with their respective returns and refunds policy.
Please ensure that the item you're returning is repackaged with all the cords, adapters and documentation that were included when you received it.
There are some items, however, that are ineligible for return, including:
Opened software*
Electronic Software Downloads
Software Up-to-Date Program Products (software upgrades)
Apple Store Gift Cards
Apple Developer products (membership, technical support incidents, WWDC tickets)
Apple Print Products
*You can return software, provided that it has not been installed on any computer. Software that contains a printed software license may not be returned if the seal or sticker on the software media packaging is broken.