In TurboTax, where do I enter a refund to a customer in order to adjust my total Income?

Are you referring to a refund of self-employment income?  If so,

• At the screen Your self-employed work summary, click Edit.
• At the screen Here's your info, scroll down to Other miscellaneous expenses.
• Click Start / Review to the right.
• Create the expense line and enter the expense amount.

Thanks for the response. TurboTax previously provided a data entry point for a specific customer refund line that was placed in the upper portion of Schedule C after the gross income. I guess just entering it as a miscellaneous expense will work just as well.