I will also point out that stopping the free employer money is between you and the employer. If you continue to take the free employer money, you will have money in the HSA to pay for medical expenses or withdraw as excess. It will be added to your taxable income (as if your employer had given you a raise instead of putting money in your HSA) but you won't pay a penalty if you spend it for qualified medical expenses or withdraw it as excess contributions. The IRS does not require you to send the money back to your employer. Any obligation to your employer is between you and them only. (For example, if you have to certify you are eligible to get the free money, you might get in trouble if you don't tell them otherwise. But that's between you and them, the IRS doesn't care.)
