What's the simplest way of "resetting" multiple linux clients to restore the default state of a fresh install?

We have 6 linux clients (mint) which are used for training. Courses might run anywhere from a few days to multiple weeks.

They want a "one button press", as in very quick and easy, way of resetting all the clients back to their fresh install state when a course is over and it should be done remotely from a linux server they're all connected to. What would be the easiest way to achieve this, do you have any advice?
Would you save a fresh mint image on the server and distribute it to all clients each time and if so what would be the easiest way to do that?
Thank you very much