No matter what we say or think, he’s president until the supremes say otherwise or he loses next month.
Not even the SCOTUS could take away his presidency, that’s the function of Impeachment.
I am glad to see others with the opinion that the notion of Obama *not* legally being president is a non-starter.
As to the OP, Obama won the electoral college, was affirmed by congress and sworn in by the CJOTSCOTUS — which rendered any notion of him not being eligible moot. The only thing left was for a state by state fight on eligibility for being on the ballot.
There. Fixed it for you.