Clean up for my garden

Minor projects needed to be done in the garden before, so the workers removed some small trees before they started the work. In fact, it took half an hour every week for 6 months, I was trying to clean them out, but there was little progress. Finally, the workers used a soil piler for half an hour, and even the roots were completely removed. There is something that need to be done by professional labor. Without them, even if the miscellaneous trees are cleared away, they will regenerate, and the roots must always be cleared away, or the tree will be killed with poison.