What is the process by which insects grow by getting rid of their old exoskeleton?

It is more like because insects grow, they must get rid of their old exoskeleton. Imagine if you took a small plastic box and put a water balloon inside. The plastic would be like the exoskeleton and the water balloon would be like the insect's organs. If you add water to the balloon eventually it will fill the whole box and start trying to pop the box open. That is like an insect. Their bodies grow but the exoskeleton is too hard to stretch or grow. Therefore, they shed their exoskeleton and grow a new one that fits them.