I want to revert to an older software version on iPad Air?

Before you start: Make sure that you have backed up everything to iCloud or iTunes. It only takes a few minutes and will protect your data from being lost.

1. First of all, download the necessary IPSW file. It is an Apple Device Software Update file.
2. Connect your iOS device to your PC/Mac with a cable and launch iTunes.
3. Click on the tiny iPad-like icon in the top left corner of the iTunes window.
4. Now click on the Restore iPad button while holding down the left Shift key (Windows) or the left Option key (macOS).
5. Select the IPSW file you downloaded in step 1 and let iTunes perform the restore.

Once the downgrade is complete, you'll see the Hello screen on your iOS device. Now you can set up your iPad as brand new, or restore from a previous backup to get started from where you left off.