Re: Adjustable wing on slalom ski fin
If you aren't running a slalom course, I'd remove it entirely. It will just wear you out because its primary purpose is to help slow the ski down when making tight-radius turns (like going around a "ball" in a slalom course). If you do leave it on, try to set it as parallel/neutral as possible to the ski to avoid it having a ton of impact on your skiing until you decide to utilize it.
Side note: many professional skiers leave it off in the slalom course as well, as a matter of personal preference