From this interview. I am somewhat doubtful that Romney would have the votes to do this, unless the GOP somehow takes the House, and maintains the Senate. Even if both of those conditions happen, certain popular provisions–such as guaranteed issue and community rating–will likely survive in one form or another (even if enacted in a separate law not called the Affordable Care Act).
Update: Thank you to commenter Juan for the correction. The GOP already has the House, they would need to also take the Senate. Slip of the keyboard.