How to Downgrade IOS 10 to IOS 9
We’re fans of iOS 10 , but not everyone likes Apple’s latest operating system . If you want to go back to iOS 9, you have a limited time to do that, so you should do it now while you still can.
Step one: back up your phone
To go back to iOS 9.3.5, you need to erase data and then restore your phone. Therefore , you will want to back up your device first using iTunes or iCloud . However, you cannot restore a full iOS 10 backup, so either restore it back, which you did before the update (you made a backup, right?). Otherwise, you’re starting from scratch here, plus the iCloud data you have.
Step 2. Download iOS 9
You need to manually download the iOS 9 file to your device. Go to IPSW Downloads , find your device and download the latest iOS 9 they offer. This will download the IPSW file, which is the iOS 9 operating system. When Apple stops allowing iOS 9, you will no longer be able to download it.
Step three: restore your device
Finally, connect your iOS device to your computer, open iTunes, then click your iOS device in iTunes.
Hold down the Option key (Shift-click on Windows), click the Restore iPhone button in iTunes, then select the IPSW you downloaded in step two. Your iPhone will be cleaned and restored as if it were a new device.