People prefer used insulation blowers to pump in the materials in the attic or wall space to keep them warm but occasionally it might have to be replaced or removed due to many reasons like,
Insulation is contaminated
Too much insulating material which may cause restricted air-flow
Smoke damage, leaky room or damaged by pets or other animals
Mold growth
Removing the insulation is a tedious task and usually, professionals are hired for this. They have special equipment for these tasks. For example, to remove loose fit cellulose the removers use used insulation vacuums, usually powered by an industrial generator or a diesel engine.
https://www.coolmachines.com/products/used-machines