Should I go to US just to study 12th grade?

So I'm an Indian student currently in 12th grade, and I have a green card, and I have been going back and forth for like 4 Years so that I won't lose my green card, but the last time I went they warned me and said that it was my last chance and now I'm thinking to study rest of 12th grade and then do college but I think that I won't get into any good college like anything other than communtiy college if I dont have any preparation for it cuz applications start at the start of 12th right so what should I do???😭😭