Some legend entries get added automatically when you apply different templates.
The Opposite entry is a default setting of the System Template. To remove it, follow these steps:
- Click on the settings icon on the right side of your map
- Select Customize defaults from the menu
- Delete the word "Opposite" from the text box behind "Opposite connection label" (or change it to something else)
- Click Save in the yellow bar at the bottom of the Settings menu
You're all set!