Your options are to return it to Apple for a full refund if you still can, to trade it into Apple for whatever they will offer you for it, or to sell it yourself and then use the funds to buy what you wish.
Apple Store Returns & Refunds. Click here to read --> http://www.apple.com/shop/help/returns_refund - For the USA "You have 14 calendar days to return an item from the date you received it." The return terms may be different in some countries.
To get more information about the "Apple Trade In" service click on the link --> https://www.apple.com/shop/trade-in
- Read the FAQ at the very bottom.
- Start a trade-in by clicking on a device in the section "Select your device to get a trade-in estimate" - Smartphone, Tablet, Computer, Watch, Other devices (recycle only)