That is a blatantly false statement.
Sorry, I overstated.
It is not possible for parents to renounce citizenship for a child. It is possible for an older minor to renounce citizenship for himself, under rather strict regulations.
Obama would most definitely not have qualified to do so when he was living in Indonesia. The general minimum age is considered to be 14, not 6 to 10.
http://travel.state.gov/law/citizenship/citizenship_776.html
F. RENUNCIATION FOR MINOR CHILDREN
Parents cannot renounce U.S. citizenship on behalf of their minor children. Before an oath of renunciation will be administered under Section 349(a)(5) of the INA, a person under the age of eighteen must convince a U.S. diplomatic or consular officer that he/she fully understands the nature and consequences of the oath of renunciation, is not subject to duress or undue influence, and is voluntarily seeking to renounce his/her U.S. citizenship.
G. IRREVOCABILITY OF RENUNCIATION
... (Section 351(b) of the INA provides that an applicant who renounced his or her U.S. citizenship before the age of eighteen can have that citizenship reinstated if he or she makes that desire known to the Department of State within six months after attaining the age of eighteen.