The issue for holding office is natural born citizen,(for which I believe Obama does not qualify), but I do not know how anyone can state with surety that Barry is not himself an undocumented worker.
I think (from what I understand, and I may be wrong) that his Indonesian citizenship came because he was adopted by Soetero. However, because his mother was an American citizen and he had, at some point, been considered a minor child of an American citizen, when he attained the age of 18 he would have had to make a specific option to retain Indonesian citizenship. I’m not sure we permitted dual citizenship with Indonesia at that time, or maybe even now.
But if he did nothing, he would then simply be an American citizen. (However, unless he was actually born here, he couldn’t legally run for president...)