Student report cards are created for all students who have been enrolled in that student group at some point during the academic year, so there isn't a way to remove a report card for a single student.
When you add a student group (e.g. Year 11), it will add all of Year 11. If you want to exclude one student (for example if they have left), you would need to either:
- Add all the students in the Report Cards tab within the report card individually
- Create a custom group of the students for who you want to create report cards. You can see how to do this here: How to create and use Custom Groups