A Remove Class in education was a group of students at an English Public School who were prevented from going up with their peers in order to receive extra tuition. In Frank Richards' Billy Bunter series the Remove Class are the focus for all the stories.
In some public schools in more recent times, e.g.Shrewsbury School in the 1980s, The 'Remove' was the last year before the sixth form, in which students did their 'O' level exams. It was the equivalent of the modern Year 11.
References
Remove (education) Wikipedia(Text) CC BY-SA