Question

how do decomposers perform the tasks of cleaning the environment​

Answer 1

here is your answer

Decomposers and scavengers break down dead plants and animals.  Decomposers are very important for any ecosystem. If they weren't in the ecosystem, the plants would not get essential nutrients, and dead matter and wastewould pile up.

Answer 2

Decomposers decompose the harmful substances and prevent them from spoiling the environment.