post 'dig your own pachysandra' on a site like craig's list or freecycle, and chances are one of us scavangers will come collect it (most of my plants are refugees, actually- my plant budget is about $50 a year)

otherwise- pull it up, and dump it in a trash can, not on the ground. then, mulch that bed heavily, and be prepared to pull up anything that shoots up from left over roots.