What would you do to end overpopulation?

You'd only be able to do it by taking away freedoms. If that was needed then I'd make it so that you can only have one child. Not everybody wants children or has them so that would reduce the population atleast a bit.

Or I would make it so that only certain people were allowed to have children. If you have a criminal record then you can't have children, so thieves, murderers, rapists, drug abusers, and so on can't have children. Those that can have children must be evaluated on if they're capable or not.

If people have children that aren't allowed to then they are given prison time, lengthy prison time, same goes if you have more than one child except for the cases in which you are carrying another child for another person who is allowed to have children but can't due to medical issues.

Essentially you'd have to take away freedoms for any method to work for definite.