sudo add-apt-repository ppa:ubuntudde-dev/stable sudo apt update sudo apt upgrade sudo apt install ubuntudde-dde reboot Removing... sudo apt remove '~ndde-.*' '~ndeepin-.*' startdde ubuntudde-dde '~nxscreensaver-.*' sudo apt autoremove sudo add-apt-repository --remove ppa:ubuntudde-dev/stable reboot