You have a few options with it. Keep it, but well away from the others, and let it finish for smoke with seeds. If it finishes ALL the way through, it's still good smoke, just have to pick through it a bit. You can harvest when it looks decent, pistils receded, trichs looking nice, and make some good butter, or hash, or oil, lots of things to do with it still. If you only have limited area for growing and can't keep it somewhere else with even a few CFL's or something, then you may be better off just getting rid of it altogether. If the others haven't been pollenated by it yet, they will be soon if kept together.