Unfortunately, you cannot flat tow a Prius of any year, make, model, or trim due to its hybrid underpinnings. Because the drivetrain and powertrain are connected to electric motors, the Prius can suffer damage to the transmission, engine, and even the electric motors themselves.
If you must tow your Prius, you essentially have one option: a flatbed trailer. However, one large enough to haul a Prius can cost upwards of $5,000 or more. As a result, you may just want to have another family member drive behind if possible—at least the Prius gets great mileage!