Both forms are correct. Split infinitives have been used since the 1300s. More information here: https://www.thoughtco.com/split-infinitive-1692127 [excerpt] "The split-infinitive rule may represent mindless prescriptivism's greatest height. It was foreign. (It was almost certainly based on the inability to split infinitives in Latin and Greek, since they consist of one word only.) It had been routinely violated by the great writers in English; one 1931 study found split infinitives in English literature from every century, beginning with the fourteenth-century epic poem Sir Gawain and the Green Knight . . .." (Robert Lane Greene, You Are What You Speak. Delacorte, 2011)

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Thanks for your comments

Chris has given you the answer. Traditionally ... not to eat is correct as "to eat" should not be split with other words. to not eat, to boldly go, to <any adverb> verb ... are known as splitting the infinitive, by putting in between, another word or words. Common and frequently heard, yet, technically less desirable, at least for those who care about grammar.

I am not a native speaker, but upper C2 level. Number one is correct. Number two is not, it sounds very weird. if you use a prefix like "dis" or "un" you could use it. E.g.: "Try to disarm him".