The easiest way to remove a whole disk set in Slackware is to mount the Slackware CD, navigate to the directory containing the packages you want to remove (in this case /x) and simply do "removepkg *.tgz".
The steps would be:
Code:
mount /mnt/cdrom
cd /mnt/cdrom/slackware/x
removepkg ./*.tgz
If you did a full install, you would probably want to repeat that procedure for the xap set as well, which contains programs that depend on X.
Of course, for that matter, if you have done a full install there will be plenty of other installed packages that you more than likely don't need aside from X.