If you got your health care from an Obamacare exchange and received Form 1095-A, you must include it to your tax return. TurboTax isn't giving you the credit, the program need to determine if any premium tax credit was paid to you during the year. 

When I signed up for Obamacare, I specifically told them not to advance me the premium tax credit because I am not entitled to it.  Now, turbotax it giving me the credit when I prepare my taxes.  I can't stop turbotax from giving me the credit.

You  are eligible for the credit if you bought the insurance  thru the ACA marketplace and your income is within the allowed range. So if you didn't take it in advance you can get it on the return even if the employer offered you insurance at work. 

You are not entitled to the credit if your employer offers an affordable health care plan.  My employer offers an affordable plan but I choose to get me health care from the exchange.