Hi! I am Zhihao Ma, a user of Texlive/Mactex from China and have updated my TexLive/Mactex to 2021 version. I found there are two files in the /usr/local/texlive, named "2020" and "2021" respectively. I'm wondering whether I could delete the "2020" file. Looking forward to hearing from you soon. Best wishes, Zhihao