How do I get rid of my encrypted iPhone backups to start from scratch?
To delete the backups, go to iTunes>Preferences>Devices. All iPhone backups will be listed here. Highlight them, then hit Delete.
But if you're using a Mac, I would first try to see if you can find the password in your Keychain (from discussions.apple.com):
- Go to the "keychain access " app.
- Under "Keychains" select "Login"
- Under "Category" select "Passwords"
- Scroll down and look for "iPhone Backup"
- Double click and a window opens
- Check the box that says "Show Password"
- A window pops up asking for your OS X account password
- Type in that password and voila!
The password is stored on the device!
If you can’t remember the password for your encrypted backup
You can’t restore an encrypted backup without its password. With iOS 11 or later, you can make a new encrypted backup of your device by resetting the password. Here’s what to do:
- On your iOS device, go to Settings > General > Reset.
- Tap Reset All Settings and enter your iOS passcode.
- Follow the steps to reset your settings. This won't affect your user data or passwords, but it will reset settings like display brightness, Home screen layout, and wallpaper. It also removes your encrypted backup password.
- Connect your device to iTunes again and create a new encrypted backup.
You won't be able to use previous encrypted backups, but you can back up your current data using iTunes and setting a new backup password.
If you have a device with iOS 10 or earlier, you can't reset the password. In this case, try the following:
- If someone else set up your device, ask them for the password.
- Use an iCloud backup instead of iTunes. If you don't have an iCloud backup, you can make one.
- Try using an older iTunes backup.
https://support.apple.com/en-us/HT205220