Somebody painted the door panels white and the paint is flaking uncovering the black.I would like to get all the white paint off thanks for any help Matt.

Oven Cleaner

Any particular brand?

Kleen strip sprayable paint stripper, and a stiff brush wear gloves.

Lacquer thinner works great. I used it to clean a set of panels that had overspray on them. Took the paint right off with no harmful side effects to the panels.

Oven cleaners on the market today are rather mild, compared to past days. Just any in super markets.
I've shyed away from solvents like lacquer acetone etc.
They do "wonders" for the paint, but uncertain about effects on plastics.
Especially if panels you're trying to do are nice
If the oven cleaner isn't to your liking, then do the solvent routine.

I have used the Easy Off Oven Cleaner in the yellow can with good results.

how long do you leave it on the panel ?

Just don't soak it.

Long enough so that a soft scrub brush using water will remove the paint.

thank you.

That is what I used in mine and all the ones at the body shop I worked at. If hard ABS Plastic. Unless they were dyed. Some needed to be dyed after as tgat was shy they were painted. Used Bull Dog before new Dye as adhesion promoter