you can not just convert a C-corp to a 1065 (partnership). or even a single-member LLC/sole proprietorship. there are tax consequences for the liquidation of the C-corp. See a professional
I was told that I would have to file a 2020 1120 form for a return with information to the coversion date of July 1. I used Turbo tax to file for year 2020, and was told I should be able to use Turbo tax for this mid year return.
The TT BUSINESS program handles the 1120 however if the business closed mid 2021 then you have to use the 2020 downloaded program to complete the short year return. If you used the TT BUSINESS program to file the 2020 return then you will NOT be able to transfer the information you must start a new tax file and enter everything anew. You may want to seek local professional assistance for a final short year return.
https://www.irs.gov/businesses/small-businesses-self-employed/closing-a-business