Gas Tank Liner remover

I took mine to the same radiator shop that installed it and they removed it. I don't know how they did it but they did. It let loose because the tank I bought was electroplated on the inside and I did not know it. It's so slick nothing will stick to it.
My friend works.in a rad shop. He said about hot tanking it. I'm not against paying to do that but if I could.find a cheaper solution