For files on your ipad, share, and transfer your files to a personal google drive or back them up on a physical flash drive using a Lightning to USB adapter/Lightning-enabled flash drive.
For Gmail based applications and files, use Google Takeout (takeout.google.com) to download your emails and files. You can also transfer ownership of your Google Docs, Sheets and Slides to your personal Google account. Alternatively, on a PC/mac, move your desired files into a folder. Right click the folder and select download.
For Onedrive, on a PC/mac, move your desired files into one folder. Right click the folder and select download.
For Onenote, have both your school and personal Microsoft account logged into the Onenote app. Tap and hold to select your desired pages/sections. Then select the move/copy button to move/copy the pages/sections to a notebook on your personal Microsoft account.
For Apple Notes, enable “on my ipad” folder for Apple Notes from the Settings app. While in your school Apple ID. Move your desired notes to the on my ipad folder. Switch over to your personal apple ID then move the notes to your Apple ID. (If notes remain in the “On my iPad” folder. You will lose the notes during ipad reset)
For other 3rd-party applications, you may try to update your username/email to retain access to your account.
For those Graduating or leaving Ngee Ann Secondary. Please do not use the iCloud backup. This is because the backup will store the DMA profile and will reapply it to the device upon activation. Please use the other methods of file backup.