We have had lots of technologies that could make (and made) many species extinct: fire, spears, guns, nets, walls in the right place that helped to trap the who

We have had lots of technologies that could make (and made) many species extinct: fire, spears, guns, nets, walls in the right place that helped to trap the whole herd. The difference this time is that we have a technology that can make extinct the species that we want to make extinct, without side effects. What complications do you foresee with this technology?