After you have enjoyed iOS 16 features, and you want to switch back to iOS 15, then we will walk you through steps on how to go about it.
Remember we advised you to make a backup before installing iOS 16? If you followed our instructions and successfully did the backup, then you can restore your files else, you are going to have a brand new iPhone with iOS 15.
=> You will need a Mac or windows PC
=> You need to restore the ios 15 back-ups on your iPhone. Note, you can’t restore a backup from iOS 16
If you don’t have a backup, you need to wipe your device as a new phone. You can download the IPWS file for your phone model from this website
=> Go to settings and turn off my iPhone feature
=> Turn off your phone, connect your iPhone to your Mac/PC using a USB cable
=> Now, while holding the alt/option key on mac or the shift key on windows, click on the Restore iPhone button
=> Select the IPWS you downloaded earlier. Then click on restore and update 》 Next and agree
=> The downgrade process should now start, once the process OS is completed, then you have your ios 15 installed.
Source VIA