Can I change just "1" error in my tax return. No need to clear everything and start over ?

Yes. Just go to Forms instead of Interview, and enter the correction. Choose Override if necessary.

Form 1099-B: Proceeds from Broker and Barter Exchange is a federal tax form used by brokerages and barter exchanges to record customers' gains and losses during a tax year. 

You can revisit the Investment section to make the correction.

• Open your return.
• Select Federal from the left menu.
• Select Wages and Income then Income and Expenses.
• Scroll down to Investment Income.