Re: the sims 3 mac high sierra

@jacindaham  The game's program files are what Origin is looking for, and those are what you dragged to the trash.  But the hidden library files are there too.  Every user account in macOS has its own Library folder.  Open a Finder Window, click Go in the upper left corner, hold down the option key, and you'll see it.

And yes, you do need to go through the clean uninstall process, or the base game will almost certainly not launch.