You can pluck the feather if you wish. It is aesthetically displeasing, and is probably going to get yanked out or broken off anyways, so pulling it shouldn't be a big deal if you do it right. Grab that errant feather with a set of needle-nose pliers right at the base, and pull it out. Don't waffle about pulling it. Just grit your teeth and yank that baby out. It's going to hurt the bird and she is going to put up a stink about it, but do it quickly and do it right the first time, and it will be over quickly for the both of you.
Good luck.