It's popular to debate if Goku could beat Superman in a fight, but fewer people ask if Dragon Ball Super's actual strongest character -- Zeno -- could eradicate Superman with a mere thought. Ultimately, with so many iterations of Superman, it is hard to definitely compare Goku's powers to Superman's powers. Post-Crisis and New 52 Superman's powers are distinctly limited, while the Pre-Crisis Superman's powers -- especially during the Silver Age -- reached such extreme absurdities he might as well be a God.
However, could any of that match Zeno's incredible power? People refer to Superman as a God, but could he actually destroy a God Amongst Gods, one who can eradicate and create universes with a mere thought, who makes Gods of Destruction quiver in terror at the mere mention of them? Let's analyze their strengths and weaknesses.
How Strong is Pre-Crisis Superman?
In this comparison, it's important to take Superman at his peak power level -- in this case, Pre-Crisis. Pre-Crisis Superman's power seemingly had no limitations. His powers were ill-defined, and he developed new ones on a regular basis. On top of that, his strength and power had little upper definition. His sneezes could tear solar systems apart. He could generate smaller equally-powerful Supermen with his fingers.
Superman's strength during the Silver Age reached absurd levels, able to tow entire solar systems behind him by a chain and toss galaxies around. He could travel faster than the speed of light and walk across the surface of the sun. While Bronze Age writers attempted to give him some more limitations, for the most part, Pre-Crisis Superman was strong enough to break the laws of matter. He truly had no limitations.
How Powerful is Zeno?
Zeno the Omni-King is the ruler of all reality itself. He does not fight, which might seemingly put him at a disadvantage against Superman. However, Zeno has two features that really make it all but impossible for Superman to beat him: he cannot be killed or even beaten and he can erase literally anything he wants.
It is reiterated multiple times throughout Dragon Ball Super that even if all reality breaks down around Zeno, he simply cannot be killed. No attack can harm him, nothing can cause him pain, even attacks that would otherwise destroy entire universes. However, while Zeno cannot be killed, he can destroy anything. Instantaneously. It does not matter what. Even immortals can be erased by Zeno, as seen with Zamatsu.
The only time anyone ever suspected that someone could defeat Zeno was during Super Dragon Ball Heroes when the villain Hearts speculated that Super Saiyan Blue Gogeta might be able to beat Zeno. However, this was never tested and Super Dragon Ball Heroes' canonicity is questionable. After all, if Super Saiyan Blue Gogeta fought Zeno, Zeno could just erase him from reality in a micro-second. The only person who can match Zeno is Zeno himself -- specifically, the Zeno from Future Trunks' timeline.
Could Pre-Crisis Superman Survive Zeno and His Erase Ability?
It is all but impossible for Superman to end Zeno. None of Superman's strength or powers can really hurt Zeno, since Zeno is indestructible even against attacks that can kill Gods and reshape reality. The question remains, however, if Superman could endure Zeno's Erase attack. If Superman could survive that, a fight between the two would end in a draw.
In Dragon Ball Super, nothing could survive Erase. Superman might at first appear indestructible, but it was possible in the original Silver Age to hurt Superman. Martian Manhunter could at times hit Superman so hard he was beaten down. However, Zeno's attack isn't really physical. It arguably could be defined as a type of magic. If so, Superman is doomed, since one of Superman's greatest weaknesses, other than Kryptonite, is magic.
However, even assuming the Erase technique isn't magic but some sort of cosmic force, Superman is still doomed. Pre-Crisis Superman was ultimately written out of reality after the Crisis on Infinite Earths event. If Superman cannot survive the erasure of his own universe, what chance does he stand against Zeno's Erase ability? Considering that Superman cannot hurt Zeno nor survive his single technique, Zeno would absolutely defeat Superman, even at his strongest.