Xfce is an open source free desktop environment for the Linux operating system, it consumes the least amount of memory and CPU compared to other Linux desktops such as GNOME and KDE, which makes it lighter and faster.
See the links below for installation and uninstallation commands:
How to install/uninstall XFCE on Ubuntu 20.04 - Linux fans (linuxmi.com) 
https://www.linuxmi.com/ubuntu-20-04-xfce.html Reprinted article, for reference only.