How can I delete all network users on startup or shutdown?

Question

I want to run this script before any student logs into the computers daily.

#!/bin/sh

mv /Users/admin /admin

wait $pid

mv /Users/Shared /Shared

wait $pid

rm -rf /Users/*

wait $pid

mv /admin /Users/admin

wait $pid

mv /Shared /Users/Shared

wait $pid

I want to keep the "admin" and "Shared" and delete the rest. I don't want to do it while students are using the computers. On start up or shutdown would be the best idea. Can I automate this?