You can’t change your mind after you convert
Under the new tax law, it is now easier to convert your employer-sponsored retirement plan such as a 401(k), 403(b), or 457 into a Roth IRA account. This is similar to converting your traditional IRA into a Roth IRA, but with one very significant difference. When you convert a traditional IRA into a Roth IRA, you can change your mind and undo this conversion (also known as a recharacterization) by October 15 of the following year.