I have never had any luck at all removing stain. Toning it, glazing
it, aging it, sure. Removing it... nope.

It sounds like the attempt with the Minwax product could be as good a
try as anything. Before I tried it, I would call the tech help line
of the stain manufacturer and ask for any suggestions.

I hadn't actually heard of a wood stain remover and was unable to find
a product like that on the net. In looking around, there were lots of
products to remove stains on wood like oxalic acid, or other light
acids with surfactants and detergents.

Are you sure you found a product that says it will remove applied wood
stain from wood?

I also noticed that you said the wood in question was pine. And to
compound things, being a six panel door, there will be stain in every
crevice, crack, joint, etc., and if the stain was applied to bare
wood, I don't think you will have much luck removing it.

Robert