can I uninstall LXDE and it not mess anything up?
Sure you can. You can uninstall just thise parts of LXDE you do not want or the whole lot. To get rid of the LXDE console uninstall lxterminal. To get rid of the file manager uninstall pcmanfm. To uninstall all of lxde uninstalling the lxde-common package should do the trick.
However it could be argued that having the lxconsole and pcmanfm packages installed does no harm since they are not shown in the KDE menu anyway (unless you look hard), and it is always handy to have a way of managing your computer if KDE should become screwed up. (Which is not unknown)
NOTE: If you installed from just the dual-arch CD without declaring any online sources during the install, then it is possible you are using the lxdm or xdm login managers in which case you should install the kdm login manager and configure your system to use kdm (MageiaControlCentre>Boot>DisplayManager) before uninstalling LXDE
