Mac not using Keychain
If you haven't given TurboTax Keychain access, you can select Forgot Password in the password request pop-up to answer your security question. That'll get you back in. Once you're back in, you can select Password Encrypt from the File menu if you want to update or remove your password altogether.
Mac using Keychain
In some rare cases if you've given Keychain access to TurboTax, you can go to Applications > Other > Keychain access > Keychains > Login > Category > Passwords > find Intuit or TurboTax and right-click Get Info > Attributes > Show Password.
You will be prompted for your Mac password and it'll show you the password you used to encrypt your TurboTax file. This is may not work for all users.
Disclaimer
Password protection of TurboTax CD/Download files is set by the user. TurboTax can't assist in unlocking the file or removing the encryption. If these steps don't help, you'll need to start over in a new file.
