Install lxsession-logout by entering the following commands in the terminal:
sudo apt update sudo apt install lxsession-logout
Description:
utility to logout from a LXDE or an Openbox session
LXSession is the default session manager for the Lightweight X11 Desktop Environment (LXDE). . LXSession-Logout is a simple utility for stopping or logging out from a LXDE or an Openbox session.
Homepage: http://www.lxde.org/
Version: 0.5.3-2ubuntu1
Section: universe/x11