Bingowings said:
He shoots it's leg off by accident and it falls over.
I assume if goes into battle with it's shields down which makes a lot of sense.
He also releases the balls by accident (knocking out many tanks and droids) and makes a hover tank veer and fire on other tanks before crashing by accident.
Seeing as Anakin destroys the droid command ship by accident too there seems to be a whole lot of happy accidents going on during that conflict, like having all the droids get their power and commands from a single source.
Presumably this is why ROTJ is the very last ever episode of the saga because George thinks Palpatine is the only thing the holding the Empire together too.
Duh.... it was The Force...