The first thing you should do before downgrading iOS 16 is to create a backup in case any data loss. You can back up with iTunes or iCloud, which are offered by Apple. Besides that, Tenorshare iCareFone is also a good choice to back up your iPhone. Follow the three steps below to complete the backup easily.
Download and install the software on your computer. Connect your device via USB and select "Backup & Restore" option from the left menu to start.
By default, all file types on your iPhone or iPad will be checked. You can Back up all data or selectively choose the file types you need.
After selected, just click the "Backup" button and wait a few second to complete the backup process. You can directly view the backup from the iCareFone.
Downgrade iOS 16 Beta with ReiBoot
Connect your device and click “Downgrade iOS” at the bottom left of the panel.
Choose "Deep Downgrade" Option.
After downloading the firmware package, you can start Deep Downgrade.
Downgrade iOS 16 with iTunes
Go to ipsw.me and download the firmware that matches your iOS device.
Launch iTunes or Finder on your computer and connect your device to a computer.
Click Restore iPhone while holding down the Option/Alt key (Mac) or the Shift key (Windows) and locate the IPSW file you downloaded earlier.