The process of removing wastes that are formed due to metabolic process and energy production from the body of an organism is called Excretion. It is an important process for all forms of life.
Unicellular organisms do not have any specialised organ to remove their waste so this removal of waste is done directly through the cell membrane by the process of diffusion.
Final Answer:-
Excretion- A process to remove metabolic waste from the body.
The unicellular organisms remove waste through diffusion.