I filed my taxes and then realized I put 100% ownership for both my spouse & I on our rental properties. Am I able to go back and change that to 50% each and refile?

You may be able to change your returns using the ReFile feature in TurboTax, but for an issue such as this it might be easier (and clearer for CRA) to complete a "manual adjustment" to both you and your wife's tax returns.

You can make the adjustment by signing in to your CRA My Account and doing it online, or by completing a T1-Adjustment form and mailing it into your Tax Centre.

See the CRA’s How to change your return page for how to make an adjustment online in your CRA My Account or by mail.