Use the Convert 3D To 2D Polylines command to convert 3D to 2D polylines.
The new polyline will take on the elevation of the start point of the 3D polyline.
To convert 3D polylines to 2D polylines
- Click Modify tab
Design panel
Convert 3D To 2D Polylines
.At the Command prompt, enter Convert3dPolys. - Select the polyline(s) to convert. Press Enter.