Q.10 Yr Old Perfect Bismarck All Fonds Green Suddenly Hanging To Ground Would Topping Save It??
bismarck palm 10 ft high was growing well looking great

Certified GKH Gardening Expert
No, topping it will kill that shoot off. It may grow a replacement, but I would not recommend doing this. If it has an infection, then cutting will be a death sentence. Unfortunately, your photo did not come through. I am unable to determine what is happening to your tree.
In the meantime, this collection of articles will help you with their care:
https://www.gardeningknowhow.com/ornamental/trees/bismarck-palm