Yes, the impact of removing all the organisms in a trophic level be different for different trophic levels. For example, if in a forest ecosystem, all the carnivores, like lions, at the third trophic level are removed, the number of herbivores in the second trophic level would go on increasing. The herbivores would eat up all the plants and turn the area into desert If all the herbivores are removed, then the vegetation would go on increasing and the carnivores feeding on them would die of starvation or migrate to other places. No, the organisms of any trophic level cannot be removed without causing any damage to the ecosystem.