Hi Travis! Welcome to the site
You can haul as many as you want with no hazmat licensing as long as the tank has been decommissioned by the propane company. Decommissioned tanks will have the valves taken out of them and all liquid will be gone. The tank will still smell like propane because of the oderant that is used in the propane. The rating plate will also be missing. They hafta remove it for their records. If it is a private tank, I would just do all that myself. Is there any propane left in it? If so you will need to hook up a deep fryer or something to it and burn it off. Make sure the burner is at least 25 feet away and it is elevated above the tank. When the fire goes out you have removed enough of the propane to vent the tank. Make sure you observe all safety requirements when doing any of these things and if you doubt anything I said then contact a propane company and have them do it for you. BE SAFE!!!!
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