More personal questions ask an adult
The answer is decomposers.
After the death of producers and consumers, decomposers (such as Actinobacteria, or other bacteria which are prokaryotes) eat that dead organisms and carbon, nitrogen, and other elements are released into the environment. It should be taken into consideration that eukaryotes (such as fungi) can be decomposers as well.
Reduce the use of items like paper towels, plastic wraps, bottled water, and newspaper.
Reuse. Items like Tupperware containers, metal water bottles, and grocery bags can be reused for multiple times.
Recycle. Items like glass bottles, plastic can, and aluminium cans can be collected and being reprocessed into new containers.