Posted: 08/06/2012 at 23:14
Depends whether you are prepared to use weedkillers. If you are, then crush the plant first (or mix a little washing-up liquid with the weedkiller - both break the plant's waxy surface) and spray it with a glyphosate-based weedkiller, being careful not to wet any plants hat you want to keep. You will probably have to repeat this a number of times.
If you prefer not to use weedkiller, then your only option is to pull it up the instant that you see it. This will take many years to work as it has extremely deep roots.