Make sure you are on the Shape tab in Edit mode.
Click the green access path line on the map to select it.
In the Marker Details pop-up > Access Path section, set the Direction field to one of these values: "Bidirectional", "Approach only", or "Departure only".
Click Save. The direction of travel you choose is reflected by the color of the access path on the map (dark green for departure only, and light green for bidirectional or approach), arrows above the path indicating the direction of travel permitted, and a direction icon at the point at which the path meets the road.
You can also right-click the access path to open a context menu and change the direction of the access path.