Royal poinciana is a deciduous flowering tropical tree prized for its beautiful red-orange booms. But this beauty can also be a pain if it is planted too close to sidewalks, driveways or other structures. Royal poinciana's roots spread actively and often break through the surface to lift, crack or otherwise disturb them. But royal poinciana's roots should only be cut if absolutely necessary. Cutting too many of this tree's roots can upset its balance, or severely weaken it.
Dig around the problem root, if necessary, to expose the entire root.
Cut cleanly through the entire root, using a sharp ax, with as few strokes as possible. Cut through the entire circumference of the root, not just the above-ground portion. Leaving the root partially cut exposes the tree to infection.
Dig the severed end of the root out of the soil if necessary. Replace any soil you uncovered.
Water the tree, keeping the soil around the tree and the severed root moist for the next month while the root heals and develops a callus.