Received 1099-S for an Installment sale. Do I still file as an Installment sale?

No, you can "elect out" of the installment method by reporting the full sale in the year of the sale.  This is considered electing out without a formal statement.  If you will receive payment in any year after the year of sale you are considered to have an installment sale.

You will report the interest income each year you receive payments until the balance is paid in full and this can be found on your amortization schedule (should be created at the time of sale).  For more information you can use this IRS link.  Publication 537-Installment Sales

To record the entire sale in the current year follow the steps here.

1. Sign into your TurboTax account (online or desktop)

2. Use the search box in the upper right > Search for investment sales

3. Jump to investment sales

4. Select the type of sale (see image attached)

To enter as an installment sale (Form 6252) in TurboTax (online or desktop):

1. Federal Taxes tab, 
   
2. Select Wages & Income
   
3. Scroll to Less Common Income
4. Select Installment Sales  
5. Check the box titled sales of real estate, cars or anything else for which you receive payments over two or more years  
   
6. Click continue & the interview will guide you from there. (see image attached)