iPad Urgent! Please help!

Hello. My son has installed cydia on a school ipad and it has to be returned to school tomorrow for the summer holidays. I really need to remove cydia from the ipad today, but I am not technical and haven't got a clue how to use an ipad, let alone load or uninstall and application.

Please could someone help me, as although I feel my son should take responsibility for having loaded the program in the first place, we are trying to get him in a different school, and references are required!

I would be forever grateful if someone could take me through it in baby-steps. Thank you.