I need some help on decal removal.
I apply decal to the Sherman, add in the softener, apply some semi-gloss coat over it to protect it.
The I realize there is a small hair-line crack in the decal that does not too very good.
I have some spare decal a I would like to remove this decal and use the spare one.
is there any way to remove the decal that has softener applied and semi-gloss coat applied over it?

Very tacky tape will lift it right off. You can also sand it and re-apply the finish. Good luck