Very few websites use Flash content anymore.
Google embeds Flash Player in Chrome and will be issuing an update soon that removes the embedded version of Flash Player, and thus removes support for Flash Player.
Microsoft embeds Flash Player in IE and Edge (as of windows 😎 and will be issuing an update removes the embedded version of Flash Player, and thus removes support for Flash Player.
To uninstall the non-embedded version of Flash Player, run the standalone uninstaller:
Mac: https://helpx.adobe.com/flash-player/kb/uninstall-flash-player-mac-os.html
Windows: https://helpx.adobe.com/flash-player/kb/uninstall-flash-player-windows.html