Go down to the planet and introduce heroin. Offer it for free, and force feed it to those who refuse. In monitored doses, so no one can OD.
Release no secrets on its damaging effects or how to make it, and then, once everyone is ridiculously doped up and addicted to heroin, suddenly remove it, without warning.
Many would die in the withdrawals, more would kill themselves, the remaining would kill off eachother, and for the few left, I would give them back thier heroin, except now, enough to where they all OD.