uninstall zoom and all associated files

As you imply, some applications are not completely removed by simply dragging it to the Trash and then emptying it. Some vendors provide an uninstall app on their web sites which can completely remove the app. Another easy to use alternative is to download and use the AppCleaner app. It is safe and effectively removes everything when used properly. I have used it for years.

Open Terminal, go to Applications → Utilities → Terminal. Type sudo uninstall file:// in the command line. Next, go to the Applications folder in Finder and drag the icon of the application you want to uninstall to the Terminal window, it will automatically paste itself. Press Enter and type your user password to remove the application, and its remaining files, from your Mac.