What do you think is the best way to decrease population?
Nuclear war.
My friend, I think you're right, but I don't think it's the best way.
I think the long-term effective way is family planning control.
Why not? Family planning is not very effective, as there will be a lot of loopholes. On top of that, it takes a lot of time to get the population under control using this method. On the other hand, a nuclear holocaust can be very effective as only cockroaches are going to survive the catastrophe. It is a very fast-acting and effective method of population control.