Well, you can try and clean it, but plastic is a gamble because even if it's not scratched, it's still somewhat porous. If you want to save it, I would "bleach bomb" the fermenter. Basically fill it to the brim with a fairly concentrated bleach solution, let it sit overnight (the chlorine would probably have all evaporated by then, but I'd let it sit anyway), and then rinse extremely well, then clean with PBW or oxyclean, again rinse extremely well, sanitize it, and then rinse again, and let it air dry. That'll hopefully clean out any and all film the organism leaves behind, kill anything, and then air drying should allow any residual chlorine from the bleach to evaporate. Should knock it out if you're thorough, but some wild bugs are very, very good at defending themselves and even if you can't see it, a tiny little colony that walls itself off in a corner and survives could recontaminate a future batch.
Now, I've followed that procedure after an accidental cross contamination with a sour beer a few years ago, and have used that fermenter afterwards multiple times without issue. So it's possible, but not guaranteed.