Here is a link for the store locations...
http://www22.verizon.com/ResidentialHelp/FiOSTV/General+Support/Account+Issues/QuestionsOne/84843.htm
Verizon has shipped two boxes to me. Both times, a UPS return label was enclosed in the package. You can either take the return to UPS, as Keyboards writes, or call UPS to pick up at your location. I did the latter both times.
You can track the return shipment via UPS's website, make screen copys or printouts of the delivery receipt.