[Jack21]

Agree with Bruce. Lacquer thinner on a rag, or scotchbrite pad will take off the paint. MEK (methylethylketone) if the lacquer thinner won't work.

That being said, a few tips.

Either of these, LQ, or MEK are more flammable than gasoline!!! And fiberglass is pretty flammable once started. So do the job in a well ventilated area, preferably outdoors. No smoking, and no lit pilot lights from water heaters nearby. And keep a fire extinguisher handy. The actual stripping should go pretty fast.

Put a mat, or lots of newspaper under the firewall area to catch the stripped paint.

Consider wearing some rubber gloves for the job, or the stripper will dry your skin.