You do not include the sales tax that you collected and then paid to the state in Line 1, per the IRS instructions shown below. These are taxes imposed on the buyer that you collected on their behalf and paid to the state. They are not taxes imposed on the seller.
2023 Instructions for Schedule C (2023) | Internal Revenue Service (irs.gov)
Line 23 instructions: You do not deduct:
State and local sales taxes imposed on the buyer that you were required to collect and pay over to state or local governments. These taxes are not included in gross receipts or sales nor are they a deductible expense. However, if the state or local government allowed you to retain any part of the sales tax you collected, you must include that amount as income on line 6.
