This really depends on what Linux distribution you use. Generally packages are treated as one unit and
you can't uninstall only part of it. On my system (PLD) all programs from kdegraphics are in separate packages.
It seems that you can't do this on your system any other way than removing those applications by hand, but beware that some other programs might cease to work after such operation.
Another, IMO safer, solution is to uninstall kdegraphics package and install by hand only those programs that you need.
You may want to ask this question on some Slackware related forum, since it's highly Slackware specific.