If they are still fairly young, you can topwork them to a more resistant variety. But, if they are on B118 rootstock, I wouldn't even waste my time doing that - just cut them down and burn them.
Actually, I doubt that burning them really does much to prevent future infections. In areas prone to FB, it is going to be present regardless of what you do. Unless you are running a commercial orchard and spraying, the best thing to do is to plant FB resistant trees. You will probably still see it even on those, but they will not be affected to a great extent. I even saw a couple of limbs with FB on Liberty this spring, but I'm not worried about it and won't do anything. It won't hurt the tree, and I will get fruit from the unaffected limbs.
Tip - There is probably no variety 100% immune to FB, but on resistant varieties the infection will likely not go into 2 year old wood, and generally fewer limbs with new growth will be affected. Heavy fertilization stimulating rapid new growth will cause FB to be worse in years when it flares up.
Best wishes