You are considered as a resident for the year of 2020.  If you meet the tax treaty requirement, you can claim the exemption on your Form 1040.  Both nonresidents and residents can apply the tax treaty benefit on their taxes as long as they meet the requirements.  

To enter the tax treaty exemption in the program, here are the steps: 

• Enter your income as usual.  
• Then enter the treaty-exempt amount as negative amount (e.g. -5000) under Federal Taxes / Less Common Income / Miscellaneous Income 1099A, 1099C / Other Reportable Income
• Download and fill in a Form 8833 from the IRS to claim an exception.  https://www.irs.gov/pub/irs-pdf/f8833.pdf
• You cannot e-file.  You can still use the TurboTax program to prepare your tax forms, but you need to print them out and submit them to IRS by mail along with Form 8833.

Thank you very much for your reply! I wonder that besides form 8833, are there any other documents I need to submit to prove that I was on F-1 before 6/15/2020? 

You might include some paperwork to prove you were on F-1 prior to becoming a resident alien. The IRS loves documented proof and paper trails. 

Got it! Thank you very much!