Q: create non-encrypted backup without previous password

No, encrypted password cannot be overwritten otherwise it is useless.

Your only option is restore as new.

If you encrypt an iPad backup in iTunes and then forget your password, you will not be able to restore from backup and your data will be unrecoverable. If you forget the password, you can continue to back up and use the device, however you will not be able to restore the encrypted backup to any device without the password. You do not need to enter the password for your backup each time you back up or sync.

If you cannot remember the password and want to start again, you can use a SmartKey iTunes Backup Password Recovery to unlock iTunes backup password at first.

From this support document http://support.apple.com/kb/ht4946

iTunes and encrypted backups

In the iTunes Summary screen, select "Encrypt iPhone backup" if you want to encrypt the information stored on your computer when iTunes makes a backup. Encrypted backups are indicated by a padlock icon, and a password is required to restore the information to iPhone. You may want to write down the password for your backup and store it in a safe place. If you use a Mac, when you set a password you can select to store the password in the keychain. With iOS 4 and later, you can transfer the iOS keychain backup to a new device if you encrypt the backup.

Warning: If you encrypt an iPhone backup in iTunes and then forget your password, you will not be able to restore from backup and your data will be unrecoverable. If you forget the password, you can continue to back up and use the device, however you will not be able to restore the encrypted backup to any device without the password. You do not need to enter the password for your backup each time you back up or sync.

If you cannot remember the password and want to start again, you must perform a full software restore and when iTunes prompts you to select the backup from which to restore, choose set up as a new device.

http://www.elcomsoft.com/eppb.html

I have the same problem. Now, what I want is create a new backup WITHOUT PASSWORD. I don't care about the old backups. I deleted all of them. So, please stop complaining about the compatibility of the previous ones. Why can't I turn the password off for a new backup, without the old password, even though I have full control of my phone?

If you have read the whole thread, you should know why, anyway below is what you should do.

If you cannot remember the password and want to start again, you must perform a full software restore and when iTunes prompts you to select the backup from which to restore, choose set up as a new device.

Has anyone figured this out. I'm in the exact same boat. Worst thing is. I've never actually clicked encrypt in the first place. I've never backed the phone up to iTunes in the past!!!

it seems like the worst security feature ever. Ive been on the phone to a senior apple support staff who couldn't explain why it was there when there was no backUps. And all ur trying to do is create a new back up!!!

Since 2009, I've been using many iPhones (3G, 4S, 5, 5S, 6, 6S & 6S Plus) and every versions of iTunes till now, encryption is never enabled.

Encryption is a choice for your own devices and is not mandatory.

You have to set it up yourself, it does not do it automatically. unless you're in a corporate settings where the encryption is a rule.

It's not a mystery, please read the whole thread. There's no other way than to restore as new.

If you were originally backing your device up with iCloud, it is an encrypted backup by design. While I have not tested this, I'm not sure how iTunes reacts if you change the backup from iCloud to iTunes. I wonder if that would have some effect on the encryption status. I'm not doubting your report here, but I have never seen iTunes automatically checkoff the encryption box, especially if a user has never used encryption. It is off by default, and requires user action to change.

At this point, I'm only aware of one method to remove that checkbox, and that is to ensure all backups in iTunes are deleted and the phone is restored as new. That removes all evidence of the original encryption, and should all for the creation of a regular backup. I would create an iCloud backup to ensure your content is backed up, and also ensure that all content is synced to supported applications on the computer and/or cloud services.

BlæckHole did you ever find an answer? It appears to me that this is a design flaw. Folks who want to discard the backup (so, please no one talk to me about security, the OP asks to create a -different- backup set, unencrypted) should be able to throw out the encrypted data from the mac, or make a new different set and retain the old data. We're not asking to look into that data with the lost password at all. Restoring the phone as new, defeats the purpose. You physically possess the phone, the data is on the phone, you should be able to back it up locally.

There is only one answer, and it is working as designed:

How can I turn off iTunes backup encryption?

To turn off iTunes backup encryption, enter the password and uncheck the Encrypted backup box in iTunes. Your encryption password is always required to turn off backup encryption.

You can't use an encrypted backup if you don't have the password. If you forgot your password, the only way to turn off backup encryption on your device is to erase your device and set up as new. Erasing removes all data from your device. If you don't want to erase your device, restore from an iCloud backup instead.

This from the Apple link: About encrypted backups in iTunes - Apple Support

You can make a backup to iCloud, then erase the device and set it up as a new device on iTunes in order to remove the encryption password, then erase it again and restore it from the iCloud backup you made. You can then back the restored device to iTunes.

Cheers,

GB

Restoring the phone as new, defeats the purpose. You physically possess the phone, the data is on the phone, you should be able to back it up locally.

Like someone who may have found or stolen your device might do?

I believe restoring as new, therefore insuring data security, *is* the purpose of the setting.

LACAllen, thank you for taking a second to include a scenario.
Isn't that scenario the purpose of the phone lock code though?

Encrypted backups in iTunes pre-date un-defeatable passcode locks and iCloud. Un-defeatable meaning you have to erase the device to remove a forgotten device passcode. That keeps your data safe. However, if someone removes your passcode lock and has access to your un-encrypted iTunes backup, they could "steal" your data.

Even without your device, they could restore your data to their device if that backup, and the PC/Mac it is stored on, is not protected in some way. This makes a local passcode lock ineffective for keeping your iTunes backup data safe.

All iCloud backups are encrypted, so there is no need for a "second" password. Your Apple ID and password are the key to accessing an iCloud backup. iTunes natively has no such protection. You don't have to sign in to iTunes to access any historical backups. Encrypted backups in iTunes is the solution to keeping data safe. For example, if you don't encrypt an iTunes backup, it won't back up your health and home-kit data.

Activation lock now protects your data  and prevents the device from being re-activated for/by someone else. This has seen the value of a stolen Apple device fall since its implementation.