Here's a complete guide how you can downgrade iOS 9.2.1 to iOS 9.2 firmware on iPhone, iPad, iPod touch.
Apple released iOS 9.2.1 just yesterday, and while the update is small in size and zero in terms of features, there are going to be users out there who would want to revert back to iOS 9.2 for one reason or the other. If you're one of those users, then here's complete step by step guide on how you can downgrade from iOS 9.2.1 to iOS 9.2 right away.
Prerequisites
iOS 9.2 IPSW file for your deviceiPhone, iPad, iPod touch charged all the way to the 100% markiTunes installed on your PC or MacUSB cable
Downgrade iOS 9.2.1 To iOS 9.2
1. Plug your iPhone, iPad, iPod touch to your PC or Mac using a USB cable.
2. Launch iTunes.
3. Select your device from the top left hand corner of iTunes.
4. Hold down the left Shift key (Windows PC) or left Option key (Mac) and then click on the 'Restore iPhone' button.
5. Select the iOS 9.2 IPSW file you downloaded beforehand.
iTunes will now verify the IPSW file with Apple and the downgrade process will begin. The entire process may take a while and you will lose all your data, so be vary of that fact, and backup your photos and everything else beforehand.
While we do recommend that you keep yourself on iOS 9.2.1 as it brings with it bug fixes and security patches, but we do understand some users would want to keep themselves on iOS 9.2 and wait for a potential jailbreak to arrive. While the news is hot on the Interwebs that a jailbreak for iOS 9.2 / 9.2.1 could well be on its way, but we can't be too sure how quickly Apple would patch things up.
Also keep in mind that Apple will sign iOS 9.2 for a short period of time after which users will have no choice but to upgrade to iOS 9.2.1 or stay on the firmware version which they're already on. If you wish to downgrade, then we highly recommend that you do so right away without any sort of hesitation. Furthermore, we will keep our readers updated regarding the jailbreak status and whether or not Apple has ceased to sign iOS 9.2 or not, so stay tuned to our round the clock coverage on that matter.
Be sure to let us know in the comments section below whether or not you chose to downgrade from iOS 9.2.1 to iOS 9.2.