I use WS for machine embroidery. Most of it will "tear away" from the project, then I soak in warm water. A little agitation (rubbing it together the old timey way of doing laundry) helps. If the pieces that concern you are small enough that you would have to pick them out with tweezers (not the whole sheet of stabilizer left behind like some have done) then I would just quilt it even without washing it out first. It will dissolve after a few washing, it can't be seen or felt.