True no one can PERMANTLY renounce your US citizenship for you. However, the US is a signatory to the Hague convention on international adoptions. When a US national is adopted in another country, the citizenship conventions of the adopting country, to include the renunciation of US citizenship is recognized to further the adoption inh the host country if that is required for citizenship. When the minor attains the age of 18, they are required to swear an oath of allegiance before the appropriate US State Dept official. At that point they are NATURALIZED citizens with NO natural born status. There is no evidence that Obama did that and if thatbis so he MAY be an illegal alien.
That may be true but it doesn’t matter. No one will do anything about it.