AVG Antivirus is already installed, please uninstall the previous version first

Installation Error! "AVG Antivirus is already installed, please uninstall the previous version first." It always appears this masage  
I have already Dragging or moving the AVG AntiVirus or AVG Internet Security the program icon to the Trash. I want to reinstall new free version AVG does not uninstall. Can you urgently get a help?