See 1040 Schedule C instructions page C-9 line 23
https://www.irs.gov/pub/irs-pdf/i1040sc.pdf
You can deduct the following taxes and
licenses on this line.
• State and local sales taxes imposed
on you as the seller of goods or services.
If you collected this tax from the buyer,
you must also include the amount collected in gross receipts or sales on
line 1.
