What would happen if you removed a primary consumer?

The primary consumer overpopulates, consumes all variable food resources, and starves until population balance is restored to the point that the food resources can once again support the primary comsumers.

The primary producer (which is consumed by the primary consumer) will do well, but the ecology will be negatively affected because the secondary consumers will starve unless an alternate food source is found. Example, death of owls when mice population decreases due to late spring and lack of food; next year will bring more food overall, thus more mice, but fewer owls to control. 

Yes he thought they should be left to chance why, because he thought that was the best thing to do