In some case, you can add --replace
to replace the current window manager. LXDE defaults to OpenBox.
Some desktop environment also have settings to replace the window manager (in this case, by AwesomeWM). A quick googling seems to indicate some distribution store this setting in /etc/xdg/lxsession/LXDE/default
.
However this is a bit of going in circle around the real issue here. Why run AwesomeWM in LXDE? Their feature set overlap at a rate of almost 100%. If you use lxde only for lxappearance (gtk theme mananger) and PCManFM, note that those 2 applications run just fine from the normal Awesome session. AwesomeWM itself provide the panel, wallpaper and window manager features, which leaves nothing from the original LXDE.