When you hear that a species is endangered, it's usually in the context that it should be saved before it's lost forever.

But what if the species in question is the Guinea Worm, or the Polio virus? Both are critically endangered thanks to decades of deliberate extermination efforts by humans. Both also happen to cause debilitating disease.

We've done it before; Smallpox and Rinderpest are extinct in the wild thanks to successful eradication campaigns.

And why draw the line there? In 2003, biologist Olivia Judson proposed that by wiping out 30 species of mosquito through the introduction of recessive "knockout" genes, we could save at least a million human lives annually that would otherwise be lost to malaria, dengue fever, and other mosquito-borne diseases.

So, do you believe that it's ethically right to intentionally eliminate a species from the earth?

Technically, Viruses aren't lifeforms. They're errant strands of botched RNA/DNA that hijack a cell to create replicas of themselves. Since they cannot self-replicate, they aren't alive.
Humans are the only creatures on this planet that have a need for ethics, simply as a stopgap to keep us from destroying everything in sight. Such is the downside of evolving toward intelligence and probably why its not evolutionarily favorable.

If it causes massive amounts of death or potential death then yes... Preserving an endangered species is fine but preserving human life is more important than anything so if that means that we have to exterminate harmful stuff along the way, so be it

No unless it is extraterrestrial in nature. And, only removing said organism from our planet.

So we should not get rid of any species native to our planet, basically?

I'm no biologist, but here's the thing about the mosquito: it is a substantial food source for many species, including many different birds. Instead of doing that, we could pull a Bill Gates and distribute vaccines to all in need.

And since I was so Conservative in my previous post.........
In a perfect world, I'd like to wipe out all the invasive species from the habitats we have introduced them to, that they aren't supposed to be in. No more Killer Bees threatening honeybee populations, no more of those Zebra Mussels choking up lake ecosystems, no more shitty invasive weeds etc.
It is possible. Alberta for example is rat free. We fucked their shit up and we have a rat patrol to fuck up any future wiseguys.

Not unless its a threat to humans...

What if it is the human species itself that needs to be thinned out in order to save the population as a whole?

Whatever needs to be done to help the human race should be done.