Yay is just a helper to automate the process of downloading, building, and installing packages from the AUR. If you remove "yay" from your system, the packages that were installed from AUR repositories using "yay" will remain on your system. So, if you remove "yay", the packages it installed will stay on your system until you explicitly uninstall them using the Pacman package manager. To remove an AUR package without "yay", use "pacman -Rs" followed by the package name.