Follow the steps for Downgrade iOS 11.4, iOS 11.3 to iOS 11.3.3, iOS 10.3.3. Move down your current iOS version to last iOS version using iTunes. See How, Without Computer or Mac.
Are you recently updated your iPhone or iPad with new iOS 11 Public? And need to downgrade from iOS 11 to iOS 10 last version. Here I show you how to downgrade iOS 11.3, iOS 11.2.1, 11.0.1, iOS 11.0.2 to iOS 10.3.3, iOS 11.1, iOS 11.2, iOS 11.1.1, iOS 11.1.2, iOS 11.2.2 to iOS 10 (Latest version of iOS 10) or iOS 10.0.1 to iOS 11.
Due to important data saved on your iDevice locally you need to follow the below step very carefully and get old look os iOS and Everything if fine and perfect like before you are using.
Backup is required to restore all the data back to the iOS device after downgrade to iOS 11.
This step work for iPhone X, iPhone 8/ 8 Plus, iPhone 7/ 7 Plus, iPhone 6/ 6 Plus, iPhone 5S.
Steps for Downgrade iOS 11.2.1, iOS 11.2.1, iOS 11.2, iOS 11.1.2/11.0.1/iOS 11.1 to iOS 11 or iOS 10.3.3 on iPhone, iPad
Find Disable Find My iPhone,
Go to the Settings > iCloud > Find My iPhone > Disable Toggle.
#1: Connect your iPhone to iTunes using lightning cable. (Accept trust this computer or Mac) and find the iPhone icon in iTunes after sync complete.
#2: Click on iPhone icon and open summary page, Fins Backup Now button under Backup section (Select This computer, I recommend don’t encrypt backup because during restore time you need to enter the password correctly).
Note: it doesn’t need if laptop or Mac system is own.
#3: at the same time be ready with latest iOS 11, iOS 10 (iOS 10.3.3 .ipsw or iOS 10.3.2, iOS 10.3.1, iOS 10.2 or iOS 10.x) firmware file to save to your local drive. Download iPhone ipsw from here. iPad ipsw, iPod touch ipsw file.
Put your iPhone into recovery mode,
iPhone X, iPhone 8/8 Plus: Press and Hold Volume Down button + Side Button until apple logo on iPhone screen. and iTunes says your iPhone detected in recovery mode.
iPhone 7/ iPhone 7 Plus: Press and Hold Power button and Volume down button until you see Apple logo to next lightning cable connecting to iTunes logo.
Prior to iPhone 7 (iPhone 6/6S/iPhone 5S): Press and Hold power button + Home button until you see Apple logo and then cable connecting to iTunes logo.
Press buttons for 10 seconds then release the Power button but continue to Home button your iPhone (for iPhone 7 or Before) and (Volume Down button for iPhone 6 or earlier) until jumped into recovery mode.
Now iPhone is in restore mode, Click on Options + Restore button on Mac
Shift-Click + Restore button click for Windows.
Browse downloaded .ipsw file from your local drive.
Wait for restore completed, all the data you will get back (Settings and Data).
Now you are done!
Hope you will update your old iOS version with new iOS 11 or later new iOS 11.x version (Go to our install iOS 11 on iPhone) with awesome features.