Generating EXCEL - CSV file modifying script

Hi guys
Let me first say Im not much of a database guys (but I wish I was), so something I might not know of the bat, but im trying!

I have a website that students come in and register for sessions (summer 2006, fall 2006 etc…) and then their name goes to a database.

Now school administrators can come in and there is a script installed that generates a CSV file which they can view of their students.

The Task:
so now we have students from 2006, and I want to delete them, only keep those registered for 2007. How do I either delete the students from the database or keep them from showing up when the excel file is being generated?

I’l attach the files!