Depends on what kind of dino you have... if it is photosynthetic, turn your lights out and quit feeding for a few days. Add some macroalgae to a refugium.
If it is non-photosynthetic, stop doing large water changes, siphon out as much as possible and hit it with a dino clean up crew. It will either go away on it's own or you may have to break down the entire tank like a few others on these boards have had to do.
To figure out if it's photosynthetic, turn your lights off for a few days and see if it dissipates or weakens.