Apple Developers who have update their iOS devices to iOS 9 beta 1 can now downgrade from the iOS 9 Beta to iOS 8. Currently, iOS 8.3 is the stable version which Apple is signing.
iOS 9 beta is currently available only for registered developers and will be open for public testing in July.
List of iOS 9 Compatible Devices
iPhone 6 Plus
iPhone 6
iPhone 5s
iPhone 5c
iPhone 5
iPhone 4s
iPad Air 2
iPad Air 1
iPad mini 3
iPad mini 2
iPad mini 1
iPad 4
iPad 3
iPad 2
iPod touch 5
How To Downgrade iOS 9 beta On iPhone, iPad, iPod Touch
Take a backup of all your data before you go ahead with the downgrade iOS 9 beta 1.
1. Download the latest version of iOS 8 for your iPhone, iPad, iPod Touch. Currently, latest version is iOS 8.3. Download iOS 8.3 For iPhone, iPad and iPod Touch.
2. Connect your device to your computer and launch iTunes.
3. Put your device into DFU mode by following the instructions below:
* Hold down Power (corner) button for 5 seconds.
* Without releasing the Power button, also hold down the Home (bottom center) button along with the Power button for 10 seconds.
* Without releasing the home button, stop holding down the power button for up to 15 seconds.
4. Windows users will have to hold Shift key and then click the “Restore iPhone” button. Mac users will have to hold down the “Option / Alt” key.
6. Select the IPSW file which you had downloaded above.
7. Wait for few minutes until iTunes downgrades your iOS device to iOS 8.3.
You have now successfully downgrade your iOS device from iOS 9 beta to iOS 8.3.