Disconnecting pool heater, gas line question

[brew4eagle]

I'm taking out an old, busted pool heater. Didn't work when we moved in, no plans to replace it in near future. I've attached a picture of the liquid propane line that has a ball valve and then a plug valve (?, turquoise colored part in pic) on top of that. Would you recommend capping the line on top of the plug valve with a black iron cap; or would you also remove the plug valve and put a brass plug in the bottom brass ball valve?

 

[JoyfulNoise]

Remove the regulator and cap it at the ball valve with a brass cap. Make sure you get the correct cap from the hardware store (it looks like a swage or flare fitting...take a picture with you). You can keep the regulator if you ever plan to use it again (that size regulator runs about $60-$80) but leaving it out in the elements will trash it.

 

[PoolGate]

You also may have a shutoff on the other end.