i want to reset notes password in my icloud backup only

That's an issue you can't get around.

From the Apple Support Document about using a passcode for notes:

Set up your notes password:

Before you can lock your notes, create a password that you can easily remember. And make sure that you give yourself a password hint. If you forget your password, Apple can't help you reset it.

If you access your iCloud notes on more than one Apple device, you'll use the same notes password to lock and unlock all of them.