Nonono Saitama can defeat Goku with an one powerful punch, although this is not a legitimate ability of Saitama. Saitama was never a serious fighter. Saitama is extremely powerful, yet he is nothing near Goku's level of power. Saitama's accomplishments pale in comparison to those of Goku. He could probably take down the entire U.S. Army with his bare hands if they came after him.
Goku has been known to fight against multiple opponents at once, using different techniques on each person. Saitama only uses one attack, but it is so powerful that it can defeat even Goku. Saitama's battle with Goku is more of a demonstration of how awesome Saitama is than an actual fight. Even so, Saitama does hold his own during their bout. After being defeated by Goku, Saitama realizes that fighting him would be pointless and decides to find another way to deal with Earth's heroes.
There have been many cases where people have said that they will fight Goku until there's no one left, but none of them ever actually happened.
Saitama does not have the capacity to defeat adversaries with a single punch. He simply happens to be able to do so against the universe's enemies. Goku from Dragon Ball and Saitama from One Punch Man are two of anime's most powerful characters. It would be surprising if one did not exceed the other in some way.
Goku has already fought and been defeated by Saitama during their first meeting. However, since then, both men have gone on to face off again and again in subsequent episodes. In almost every match-up, Saitama proves himself to be a more capable fighter than Goku. This indicates that even though Goku is incredibly strong, he cannot beat Saitama alone. Instead, he needs his allies to help him fight against Mecha-Tron and Super Android 13.
Even after being augmented by Perfect Cell, Goku was still no match for Saitama. The latter also notes that despite how strong Goku appears to be, he is actually quite weak compared to many other characters in the series. Despite this, Goku continues to fight against overwhelming odds because it is his destiny to destroy evil once and for all.
As you can see, One Punch Man is stronger than Goku. SSJ1 Yamamoto is indeed the strongest character in the series and he only gets stronger as the story progresses.
Goku has sparred with nearly every character on the show who can throw a punch at this point. He may not always win the first time, but he always becomes the strongest in the end. Still, this is an anime, and Goku would not be where he is now without the support of his devoted friends and family.
Goku has fought over 100 times in the entire history of the series and has never lost once. Not only that, but he has also never been knocked out of a fight. He has been known to have his arms and legs broken, but has always recovered within seconds.
Gohan has never seen him lose a fight either. Even when he was younger, Goku showed such incredible strength and stamina that Gohan often wondered how anyone could beat him. As he grew up, Goku taught him everything he knew about fighting and Gohan has been trying to one-up his father ever since.
Goku's record speaks for itself - he has never been defeated or even injured. This proves that even though Earth's strongest man may be gone, he will forever remain one of the greatest fighters in history.
While Goku is an unfathomably powerful fighter in his own right, the cosmos and even the multiverse are constantly producing warriors he cannot beat. Goku isn't invincible, as various opponents in Dragon Ball Super have succeeded to halt the Super Saiyan. However, none of them has ever managed to kill him.
Goku's power may be limitless, but so is his age - he is already over 100 years old - and even he has his limits. It's possible to defeat him if you take care of his weaknesses, but it's also important not to underestimate him.
In conclusion, yes it is possible to defeat Goku in Dragon Ball Super.