If, for some reason, you believe that upgrading to the firmware version 10.3.2 was a mistake on your end, then you will be pleased to learn that you can downgrade back to the older iOS 10.3.1 firmware right away. Apple released the iOS 10.3 update in mid-March. The new iOS 10.3.2 update arrived in the middle of May.
Unfortunately there is no way to go back to iOS 10.2, which you can jailbreak. It isn’t possible to move to any firmware version of your choosing. Because once Apple has closed the signing window, you are stuck on the latest firmware for good. So, keep that in mind. Apple closed the option to downgrade to iOS 9 long ago, but you can still downgrade to iOS 10.3.1.
Before You Begin
Performing a downgrade will erase everything off your device. So, you should make sure that your iPhone or iPad is backed up to your computer. Also, make sure you disabled Find My iPhone.
Now Perform following steps;
Step 2: Plug into your Mac or PC using a Lightning cable.
Step 3: Launch iTunes. If you haven’t downloaded iTunes already, then head over to: apple.com/itunes
Step 4: Download iOS 10.3.1 ipsw files for any of the iPhone or iPad here. If the row is green and there is a check in the Apple Signing Status, then you know that you can continue.
Step 5: On launching iTunes, you’ll see your device listed on the top left hand corner of iTunes. Click on it.
Step 6: Hold down the left SHIFT key (Windows) or the left OPTION key (Mac) and then click on the Restore iPhone button in iTunes.
Step 7: Select the iOS 10.3.1 firmware file and the downgrade iOS 10.3.2 will begin. iTunes will first of all extract the firmware file, then restore your device.
Once that's done, You will be presented with the iOS welcome screen, sign in with your Apple ID and you have a blank iPhone on iOS 10.3.1.