iOS 9 Beta was recently released for testing by the iPhone and iPad users. It is easy to downgrade this back to iOS 8.4 if you do not like the beta iOS 9.
If you decide to downgrade, that’s no problem since you can also upgrade it again later when the final release is out or whenever you want to.
All you need is a windows or a mac computer with iTunes installed on it and a USB cable to connect the device with the computer.
Follow the steps listed below to downgrade back to 8.4
Downgrading your iPhone/iPad to iOS 8.4
Before continuing with this guide, make sure you have a back up of your data either on iCloud or on iTunes.
1. Turn the iPad/iPhone off by holding the sleep/wake button. When the slide to power off appears, slide it to turn it off.
2. Hold down the home button and continue holding it until you Plug your iPhone/iPad via the USB cable into the computer (windows or mac) with iTunes installed on it.
3. This should get you connected to iTunes with your device in Recovery Mode. We need to get this into recovery mode to downgrade.
4. On iTunes, choose Restore and then choose Restore and Update.
5. Click next for the iOS 8.4 software updater.
6. Proceed with the steps on screen to finish the restore. If it boots into iOS 9 then repeat the steps above.