how to destroy a tree stump?
Deprive it of light
Depriving the stump of light is an efficient technique to speed up the stump decomposition. First pierce the stump in several locations, as deep as possible with a drill. Fill the stump with a large amount of water in order to promote fungal growth. Cover the stump with a tarp and weight it down to prevent the tarp from being displaced by weather related events. This will make it completely soft in a matter of a few months (depending on the initial size of the stump). After that, you will be able to cut the rotten wood with an axe, and turn the soil with a pitch-fork or a spade.
You also have the option to pierce or split open the stump to add a piece of hard cheese in it. It will attract worms and other parasites to eat it, and then eat the wood.