Helmet M16

[Kohima]

I’ve had some success in the past with masking tape. Gently rubbed down onto the decal, it removed most of it cleanly, in one go.
Of course, it depends how well fixed it is in the first place, but it was good for getting the bulk of it off. I still had to flick and tease the little bits off with a light spirit and scalpel point, under magnification, over several hours though.
Patience and a light touch is key, though there will always be a trace...

All the best,
Bob