how can i remove the backup password on i tune

you can't

The only way is to restore as new

Or if you have a back up BEFORE the password was set

"The attached device has a backup password set. You need to disable the backup password in iTunes before you can continue. Start iTunes, remove the backup password and start this Program again".

When I upgraded my iPhone 4, I got the above message to remove my backup in iTunes. You can find support via Google search:

"The attached device has a backup password set"