How do I clear an amount showing on IRA contributions? I mistakenly added my 403b contributions - and have removed the amount, but a negative balance remains

You can try to delete the form.

Open your return in TurboTax. 

• In the left side bar, select Tax Tools> Tools.
• In the pop-up window Tool Center, choose Delete a form.
• Select Delete next to the form/schedule/worksheet and follow the onscreen instructions.

The form that you need to delete is the IRA Contribution Worksheet ("IRA Contrib Wks").