In Ubuntu (gnome) there is an easy graphical way to disable tapping on the touchpad. However, KDE lacks such thing. But lacking graphical configuration doesn’t mean this should be difficult. All you need is the gsynaptics package. The package provides a small utility called synclient. Now you can disable tapping by doing
synclient TapButton1=0
To disable the tapping permanently you should use the following to run the command at the start of every KDE session.
echo "synclient TapButton1=0" > ~/.kde/env/disable-tapping.sh