Sorry, that's not how it works. After-tax HSA contributions are deductible from your income, that's the whole point of an HSA. You take the deduction using form 8889 (which combines all your employer, payroll and after-tax contributions) and you get the deduction for after tax contributions on line 25 of form 1040.
As a result, withdrawals from any HSA that are used for non-qualified purposes are subject to regular income tax (to recover the deduction) plus a 20% penalty.
