Can I enter my loss manually in Turbotax, if the stock with quantities is reported as "Security deemed worthless" in 1099 form? I purchased these shares on 2021 & 2022.

You can deduct worthless stock only in the tax year it becomes completely worthless. This normally happens when the corporation files for bankruptcy, stops doing business, and has no assets. Financial difficulties won't make a company's stock worthless unless there is no hope that the company will pull through.  IRS and a Worthless Security

Enter a worthless stock like any stock sale but with a sales price of zero and the word "worthless" in its description. Enter the correct cost or basis, date acquired, and December 31 as the date sold.

Where do I enter investment sales?

Thank you so much for prompt response. One follow-up question on your answer - "You can deduct worthless stock only in the tax year it becomes completely worthless". Is this mean my 2024 1099 has the statement as worthless stock. So I can file this stock as my worthless sales right?

Yes, once you know the stock is worthless, you can deduct it.