@Jordan isle How was the elimination of Muggles supposed to help?

Ask Voldemort

He was a blood supremacist, and thought wizards (especially Purebloods) were superior. A lot of the way he and the Death Eaters were written was inspired by Nazis, and their belief that people with Jewish heritage, even a long ways back, were "tainted").

he was trying to become immortal

He was Immortal til the Last Horcrux was destroyed that being Nagini

He wanted to rule the wizarding world and destroy all of the muggles because he thought they were filthy and were stealing magic. He also wanted to be immortal forever, which is why he made horcruxes. He really honestly only liked the pureblood wizards and witches, and so he exterminated everyone who he thought was unworthy of magic.

@KAYAKOALA What do you mean stealing magic?

I mean that Voldemort and his death eaters told everyone that the muggles were taking magic away from the pureblood and halfblood wizards. He thought that they were like, absorbing the magic away from the purebloods.

@KAYAKOALA Was he paranoid? Is that what he thought that?

Maybe he was paranoid, it seems that he might have been, I'm honestly not sure. But mostly Voldemort was crazy and always told himself that the muggles were worthless and he tried to convince people to destroy muggles at one point.