This question is almost comical, as usually these metal badges fall down by themselves over time. Absolutely no "magic" metal glue to hold them in place! The amount of Linhof lensboards with missing badge for sale on eBay is absolutely impressive and almost self-explanatory.
In case you have one of the few lensboards in which the badge doesn't pop off just by letting it alone, I would try first to take it off with a small screwdriver acting from the bottom (so the damage would be less visible, should it be marred). In the rare case in which it would stubbornly refuse to fall down, I would submerse it in alcohol for a long time: it should dissolve the glue on the long run.
I wonder why you want to remove it at all, though. It should stay exactly where it is.