Where is Flash installed on OSX?
There is no stand-alone application for Flash Player like most software, as it is simply a browser plug-in. If installed, the plug-in file should be located at either /Library/Internet Plug-Ins or ~/Library/Internet Plug-Ins and should be named Flash Player.plugin.

Note if you have Google Chrome, it is built-in to the browser. In modern versions of OS X, Flash Player is no longer installed by default, so if you haven't installed it manually from another browser, it may not be on your system at all.