If you've got a heat blanket you could use that. If not a heat lamp would work, or even a clothes iron
I'd cut a hole just the size of the bridge in a piece of corrugated cardboard to protect the top from the heat, and probably use an aluminum mask over that, too. Don't heat it up too fast: the idea is to get to about 140 degrees, which is the softening point of most such glues, uniformly throughout the glue line. When you think it's hot enough (where's that IR non-contact thermometer?) turn everything off and probe the joint with something like a putty knife. It's best to grind it down as thin as you can for a ways back from the edge so that it's flexible, and will follow the glue line, but don't have a sharp edge. You don't want it to cut into wood, just follow the glue line.
Some folks like to use a hot knife. This works best if you have several knives set up as stated above. Put them in a boiling water bath, and, when they've gotten good and hot, try to work them in under the bridge. When one cools off put it back in the bath, and go to the next one. This works well in a pre-heated joint.
Glues of this type are will also dissolve (more or less) in acetic acid. You can use vinegar, which is about 3% acetic, or photographer's stop bath, which is more like 38%. The acid will react with iron to stain wood black, so use a stainless steel knife for this. If you can get some methyl cellulose to mix with the acid it will form a gel that stays in place better and doesn't evaporate as fast. This is what 'De'Glue Goo' is, so far as I know.
Water, by itself, is a poor choice, hot or cold. Usually the top wood will go to mush before the glue softens much.
If all else fails, or these treatments sound risky (they are, especially if you don't have much experience with them!) you can simply plane the bridge down almost to the surface, and scrape off the rest. Again, protect the top with a mask.