Did the post office deliver it wrong or was it addressed wrong?
If it's addressed wrong, keep it, give it away as a gift or something.
If it was delivered wrong you commited a federal crime by opening mail not addressed to you. Destruction of that mail is bigger crime. Take it and the box to the PO and explain what happened, they will tape it back up and deliver it to the right address, and they will probably have a big laugh at the guy who actually bought it.