Practically if there will be less population than Efficient and distribution of resources will not create a problem.
For example - If a Big tree ( population) have thousands of dry leaves ( distribution) coming down and getting collected nearby your house. Then you have to cut down the tree not the leaves from its branches because if you cut down the leaves it will again grow and then again it will create mess. What I meant to say is we have to see the root of the problem, not the problem.
Population graphs are not linear systems, they're chaotic. What that means is that populations don't simply grow in one direction, there are a multitude of factors that grow in different directions that gives you a final result. When Russia fought in WW2 they had a lot of casualties, those deaths still appear in populations graphs today as depressions in numbers every few years.
The massive increase in human population is due to the fact we can now mass produce resources, less people die at birth, and people live longer due to modern medicine. Population culling of any kind wouldn't result in more resources for everyone, it would actually result in Economic downturns because there's less people producing (or working and consuming).
A lot of the problems mentioned in the post are efficiency problems. Better recycling, green energy, sustainable farming, cleaning efforts, regulation of pollutants, and alternative materials for electronics. This are all things in the realm of possibility that would allow us not to destroy the planet as OP put it. Things that wouldn't go away if there are less people, we would just destroy the planet slower.