Trees, bushes, and hedges are trimmed when their branches get too large for their environment. Only trees need to be trimmed in this context. When a tree is too big for its space, its leaves and branches may block out the sun, stunting its development.
When we "limb up" (also known as "raise the crown") a tree, we remove its lower branches for aesthetic purposes rather than to improve the tree's health. Many municipalities and private homeowners cut off the lowest branches to make space for pedestrians and vehicles or to let sunlight in so grass may grow.
You could kill or severely damage your tree if you don't know what you're doing. Avoid making cuts that are too close to the main stem. These are excessively large incisions that may prevent proper healing. Don't make your incisions too deep into the trunk.
Fill the holes with enough kerosene to saturate the tree stump. Make a fire on top of the stump using the leftover wood, twigs, and small logs. Keep the fire going by adding more wood as it burns down. You can cover the resulting ash with dirt when the stump has been completely burnt.