@ZaraAdn
It absolutely isn't necessary to factory reset your Mac to get rid of all the Sims 3 files. That's extreme and not helpful to people who are not comfortable wiping their Macs. Simply
manually uninstalling is enough. Factory resetting a Mac should only be done when there are evident problems of corrupted or missing files, permissions etc in the OS. And ONLY when the user is fully confident of what they are doing.
The problem is with
Late Night, Ambitions, Fast Lane and Outdoor Living, macOS El Capitan and later versions of macOS. This is all very well documented here, at AHQ, on my site, and countless other sites, forums and social media channels. The video you refer to isn't mine, full credit for that goes to corey_0414.