Razor blade carefully if it's soft still score it out side to side should pull right out but if it's hard then patients and a steady hand.
Just spray with Krudkutter or goof-off and wipe it away with a rag and some pressure from your finger nail. If it is latex it will come right up. Don't use a scraper as it may scratch the metal.
Actually Tom, I recently had to do this and the only thing that took off the bulk of it was good old fashioned hard work and muscle.
In addition, the Goof-off does work pretty good for the lighter leftover areas.
Like Mark said, use a razor knife to cut away as much of it as you can. If you then use a stiff putty knife wrapped with a thin (T-shirt thickness) rag it will take off the rest. The rag will keep the putty knife from damaging the surface.
Using a heat gun also will soften the material as well. Just be careful not to overheat the area. Once soft then scrap with a razor blade or stiff sharp putty knife.
After after first scraping off what you can without scratching the metal, #0000 steel wool and denatured alcohol with Nitrile gloves will remove the rest.