It is quite easy for the home automotive enthusiest to remove an LPG tank from their vehicle, however decanting the LPG is illegal without a licence and very dangerous without the correct equipment. Inspect the lpg tank or cylinder, you may need to remove the inspection cover if fitted. Depending on the tank, it may have a central valve, or multivalve, or be a 3 or 4 valve tank. Each is treated in a similar way. First you will need to shut off the valve to the tank. You can then run the vehicle until it stalls to ensure most or all of the gas is out of the line, Then, make sure the ignition is off, it is good practice when working on vehicles to disconnect the battery, however it is unnecessary. To the tank you will see two lines, one is the 'fill' line (usually a braided line) and the other a copper line to the regulator. You need to unscrew and disconnect these lines. The wire connecting the tank guage needs to be disconnected, and depending on the year of the tank, there may also be be an electronic solenoid that needs disconecting. At this stage there should be nothing connecting the tank to the vehicle other than the tank mounts or brackets. If the tank is under the car, support it by use of a stand or jack and undo the mounts. Then lower the tank, if it is mounted incar, lift out. The tank can then be taken to a licenced tester, who can decant the lpg or to be inspected for restamping and orreconditioned should it be within specs.