It is a best practice to keep your return as filed for 2019.
To project what your taxes will be for 2020, I recommend instead using this IRS Tax Withholding Estimator so you can get a very clear idea of what you will owe federally.
You can contact your State Department of Revenue, for their estimated tax withholding recommendations.
By submitting updated W-4 forms for the Federal and State Taxes, you can set it up as you wish--either fairly close to $0 or an estimated amount for a refund.
These are the tax brackets for 2019 and for 2020
