Go on to any computer you have admin on, get a blank usb, search hirens boot CD follow the instructions on their website to flash the drive, stick it into the pc, while it's booting aka right after you press the power button spam f12 click on the option that says usb wait for it to boot, go to the bottom left click on the windowe logo click all files click the folder that says passwords 9r security run the app Windows login unlocker add a new user then you have admin on the school laptop just type administrator\username when it asks for admin
Once you have hirens boot CD running then you can start the setup of wifi connect to wifi and just use the usb as your ssd basically