I'm on 2020 version 3 now, is there any reason not to uninstall 2017 and 2018? 

I ask because sometimes when I open a file from explorer, it opens in 2018, then i get all the warnings about future versions... yadda yadda yadda. I don't want that to come up any more. 

Also on PDM standard 2020 if that's relevant for some reason.