Do you mean the PvP part? No. Once you're in, you're in. As for not doing the hunt at all ("opting out") you can 1) not open the tasks when they appear on day 1, 2) not play PIMD for 2 weeks (or the duration of the hunt) if you've opened them, or 3) don't complete any parties and just PvP or whatever you do (to not get the PvP items that obvi means not having opted into the PvP at the start of the hunt).