If you collected sales taxes and it is included in the income on the 1099-MISC, then you deduct that sales tax (which you sent to the state or to the company to send to the state) on line 23 of Schedule C.
In TurboTax Self-Employed, go to Business->Business Income and Expenses->Business Expenses->Other Common Business Expenses. You enter this in the business expenses section under Taxes and Licenses. This will populate line 23 on the Schedule C.
Please see this IRS article for more information about the tax treatment of direct sellers.
