For those wondering, ′′ how did i do it?":
I Boiled 10l of water, added 2 tablespoons of vinegar, 1 teaspoon of sodium bicarbonate, two cups of coke and half cup of lemon juice then stirred well .
Waited 3 minutes, put the pan in the solution for 45 minutes, then added a quarter cup of chlorine bleach to the mixture.
Then I brushed it with a firm toothbrush and put it back into the liquid for another 25 minutes.
I took it out, rinsed it and it looked exactly the same, so I threw it away and went out and bought a new one.
@ktdoggett
🤣 Ok, you got me. 🙄 😋 All my pans look like the first one so I was really into your removal recipe.... untill... 😂
The toothbrushbrushing sounded like a bit too much work though. 😉

@Erny

Read above comment about aluminum foil.
Oven cleaner will take that crud off the bottom of the pan.
Just cleaning after each use keeps the bowl part clean.