Yes, they did surprisingly!
I bought a set of pry bars like these
LINKY and used the small one to pry the edge of the skin up. I took the skin just over the 90 degrees so it would lift off. I think galv doors were very much in their infancy, if available at all. What I should have done was got the frames galvanised. What I did instead was get them plastic coated. I then filled them with dinitrol. The skins just sat back on and the edges folded over no bother. I had them painted in a paint shop after that. That was seven years ago, but the frames are going already
EDIT
@bluedog333
I've been looking through my rebuild pictures and it's reminded me that the skins on my new doors were also glued on. The skins came away no bother though (They were Britpart mind!)
This is the adhesive being scraped off the skin.
View attachment 251243
Frame with industrial plastic coating.
View attachment 251244
Full of dinitrol
View attachment 251245
Skin back on
View attachment 251246
I should have galvanised the frames