You can easily get into trouble when using beta software. Because beta versions are produced not for consumers and not for daily use. But if you have already installed iOS 8 Beta 5 on your cell phone and you really don’t like it you can downgrade iOS 8 to iOS 7.1.
Despite the fact that the Apple’s iOS 8 installation warning that you cannot downgrade. Follow these steps and you will not face with any difficulties.
Step1.To save your information backup your iOS device to iCloud or using iTunes so that you can recover your data from the backup if anything went wrong.
Step2. Download iOS 8 beta to iOS 7.1 firmware (.ipsw) file for your device from this link: http://ipswdownloader.com/
Step3. Connect the device operating iOS 8 beta to your laptop or computer.
Step4 .Launch iTunes and choose the iOS device from the top right corner, to the left of the iTunes Store button.
Step5. Hold the Alt/Option key on the Mac (or Shift Key on Windows) on your keyboard and click on the Check for Update iPhone/iPod touch/iPad button in iTunes. Please note that it is important to hold the Alt/Option key or Shift key when you click on the Check for Update button directly, you will get an error message that iOS 8.0 is the current version.
Step6. Select the ipsw file you had downloaded in the step 2.
Step7. iTunes will inform that it will erase and restore your device to iOS 7.1. and will verify the restore with Apple.
Step8. Click the Update button to proceed.
Step9. iTunes should now downgrade your device to iOS 7.1.
Step 10.You can also look through the video to do downgrading: