What will happen if we kill all the organisms in one trophic level?

Explanation

If we kill all the organisms in one trophic level then organisms of next trophic level will not get food (chemical energy) and the entire food chain gets disturbed. All the organisms which are dependent on these are died.
On the other hand, the organisms at the lower trophic level will increase in abundance. Due to this, ecosystem will be in imbalance.