Removing unwanted polish

I polished the flat black area on the bottom of my rear bumper of my 2008 Grand Prix with Nu Finish. Now that it has hazed over, I can't get it off. What can I use to get this stuff off?

Nu-Finish is tough stuff, a better product than many give it credit for being since it doesn't cost and arm and leg and is available everywhere.
That said, your best bet is to get some lighter fluid and an old tooth brush, soak the affected area for a bit, keeping it wet with the fluid, and then agitate with the toothbrush to get down in the grain of the plastic.
Wash off, dry and check.
There may still be a slight discoloration due to the solvents in the Nu-Finish removing some of the release agents that are in the part from production.
You may have to use some tire dressing from time to time to keep the color "looking" right.
Grumpy

Use a toothbrush or other brush and all purpose cleaner. Meguiar's Heavy Duty Vinyl Cleaner works too. As a last resort, use laquer thinner but test first in one spot.
Apply protectant , special paint, or a dye such as Forever Black or Griot's bumper dye if need be to cover any permanent discoloration.

I like using IPA or steam to remove polish residue, fortunately I'm using water based formula polish and not solvent, I hate that sticky solvent stuff

Oops, I misunderstood the question. What happened here is NuFinish, a polymer sealant containing cleaners was applied to a flat black metal surface -correct ?

The best way to remove the mess would probably be to brush on mineral spirits or a Naptha-based product like PPG Acrilikleen or Prepsol . Then towel off the dissolved sealant. Do this At Your Own Risk, of course.

Otherwise, Griot's Paint Prep or Dawn dish liquid might remove the polymer sealant .

Doug

Doug,
Thanks for your answer. Actually, the 2008 Grand Prix has a plastic rear bumper cover and the lower center portion is colored flat black. My mistake was in getting Nu Finish on that center portion. I wonder if Acrilikleen or Prepsol would damage the plastic of the bumper cover?

Neither of those products were made for use such as you need.
They are "bodyshop" products to remove waxes, silicones, etc from the vehicles surface before sanding.
Use them on your black plastic trim and it will appear to work just fine.
Then, a week or so later, you will most likely observe the black going to a grey color.
Same often happens when lacquer thinner is used (MEK), it attacks the surface of the plastic.
Can't not recommend them for your needs.
Grumpy

If the part is plastic, I'd use the APC and a stiff brush or the Meg. HD Vinyl Cleaner or equivalent .

Doug

Here is a "simple" way to know if a brand of solvent may damage trim, paint etc.
Read the label.
If it has health warning regarding a "toxic" component, usually xylene in grease/tar removers-a clorinated that is toxic/carcenigenic, it may create damage.
Usually and should, display the poision symbol on the label.
If one choses to use such a product, be sure and put on chemical proof gloves and do not inhale the fumes.
This component is a very active solvent, great cleaner, which is why it is necessary to have in products that bodyshops use.
It is not intended for "casual use" by the uninformed.
Grumpy