I'm writing a fantasy/sci-fi story. Imagine an alien race, about as advanced as any sci-fi alien race has ever been depicted in any REALISTIC medium. They're gonna target an earth-like planet. I need all human life, buildings, and cities eliminated on the surface so that the next civilization doesn't immediately realize it was recently a home to someone else. That said, we need some people who are underground to survive this 'attack' We can make these really deep if need be.
The planet is not the same as ours, but for the sake of convenience, assume it is exactly like our planet as it is today.
After the attack, the aliens will then, depending on the means of destruction, give the planet to a new human race replacing the old owners of the planet.
So basically, I need a method that would mainly clear the surface of the planet so that it could appear new to a, lets say, primitive race, but keeps people safe in bunkers, and I need it done within 10 years.
The alien race can then prep the planet for a new human race asap. They can speed along the rebuilding. We can allow the aliens to rebuild an ecosystem for the new humans if that's needs to be done. They could create land fills, throw trash into space, whatever they gotta to to make it presentable. They could travel the cosmos and repopulate/reintroduce the wildlife/ecosystem n whatnot. But if we can that can avoid this, great. This all depends on our method of destruction.