*takes an exasperated breath*
for the 86428753579754 time: they. used. quantum mechanics.
Unless they go backwards even with the science behind this trek, and the most modern time travel theories, if the kelvin crew went back in time they'd just create, thus access to, another alternate reality of their own (like they already did in the comics) but theirs would still happen, just like Tos is still happening after the kelvin timeline was created. There is no reset here. It can't be.
The whole concept doesn't exist because it's parallel realities. They'd just endlessly access to different realities but tos doesn't need to be restored.
And frankly, I'd have definitive proof that the guys at Paramount are insane if they did something like that, and thus decided to deliberately delete their own frigging trek reality preventing anyone in the future to do more with the kelvin timeline. It's suicide. What's the point of taking so much effort establishing another reality to use for stories, movies, possible series, novels, comics, merchandise etc etc..only to suddenly say, 9 years, 3 movies and a bunch of comics and novels later 'haha just kidding! You know what? We delete everything forget about it!'.
This is not an episode where they showed a glimpse of what if scenario, they are invested in this other trek and made people care about this version of the characters, why on earth should they want to eliminate it for its fans and anyone who would want to continue it? What's the point of even making another movie?
That's the worst idea of the history of worst ideas ever.