MNT: Remove duplicated altitude method from Flight class

rocketpy/simulation/flight.py

@@ -2078,11 +2078,6 @@ def w3(self):
         """Rocket angular velocity ω3 as a Function of time."""
         return self.solution_array[:, [0, 13]]
 
-    @funcify_method("Time (s)", "Altitude (m)", "spline", "zero")
-    def altitude(self):
-        """Rocket altitude Above Ground Level (AGL) as a Function of time."""
-        return self.z - self.env.elevation
-
     # Process second type of outputs - accelerations components
     @funcify_method("Time (s)", "Ax (m/s²)", "spline", "zero")
     def ax(self):