One way you can select to run just your window manager without a desktop environment such as LXDE (or Gnome or KDE etc) is to boot into runlevel 3 (which boots to a terminal), then start X and then start your window manager. I will show you the three steps I use. First, there are a few ways of booting to runlevel 3. You could add the number 3 to the kernel parameters on the GRUB_CMDLINE_LINUX line in /etc/default/grub (inside the quotation marks) as root and then run:
grub2-mkconfig -o /boot/grub2/grub.cfg
When you reboot the computer should boot you to a console. Another way is to change, as root, your default.target file in /etc/systemd/system by deleting the default.target link in that directory and creating a new default.target with the command:
ln -s /lib/systemd/system/multi-user.target /etc/systemd/system/default.target
Once your system boots to a console, then you login and as user can run xinit;
which should start X and give you an xterm. Sometimes, in the past, I have had to have an .xinitrc file (note the dot) to get this result, so if the command xinit doesn't take you to an xterm you could create a simple .xinitrc file in your home directory with the following contents and then run xinit from your home directory:
In that xterm you can start your window manager, for example:
but you should replace twm with your chosen window manager, unless you want to use twm that is.
The & runs the command in the background and your window manager should appear. There are other ways to do this and to automate it all and give it more functionality, particularly the use of an .xinitrc file which you create yourself, but I'll leave that for others. Ben.