Let’s say a student only needs two. What if they want to take three different subjects and only submit their two best scores. How does one do that?
College Board offers Score Choice, you can choose what scores to send. But, as a warning, not all colleges/scholarship programs allow Score Choice
When you log in to send your scores, you will be able to select which SAT II scores you wish to send. But, as commented above, some schools require that you submit all scores. Off the top of my head, the following require all scores:
Carnegie Mellon University
Cornell University
Georgetown University
University of California campuses
University of Pennsylvania
Rice University
Stanford University
Yale University
The above list is not all-inclusive so check each college’s website for score reporting policies. IIRC, the CB site will prompt you if a school requires all scores.