According to the law of conservation of energy, energy can neither be created nor destroyed. If this is true, why is there less energy in the top of the energy pyramid than there is in the bottom of the energy pyramid?

Energy Pyramid - "It is the graphical representation of the energy flow through the different levels of food chain, as at some level there are consumers present on the energy pyramid and then at the bottom there are producers."

Explanation:

There are two main reason that there is less energy on the top level of energy pyramid while there is more on the bottom level.

Stable and Control Population- The organisms at the high level of the energy pyramid are been supplied by less amount of energy just because they need a more control level of population so they can have enough supply of energy to all the organisms. Otherwise population will be out of control.
Source of Energy - At the bottom of the energy pyramid there are producers who supplies energy to other living life to survive so the energy is stored and produced on the lower level of the energy pyramid. As the producers are more in number and acts as the source of energy for all the living life.

Note(*To make it more logical*) -Along with that the organism at the top most level have a more complex body build up which contains more energy then the less complex form of life present on the lower level so they have the amount of energy to balance themselves with the lower level of the energy pyramid.