waylandにならないと思ったら/usr/share/xsessions/と/usr/share/wayland-sessions/の両方にgnome.desktopが有って、どっちか分からなかっだけ
Using root privilege (su or sudo) go to /usr/share/xsessions and move (mv) the gnome.desktop file to gnome.desktop.bak or whatever extension you want at the end of that file name
