Edit Mode unlocks at level 4. Tap the blue button with arrows on the left of the screen or choose a covering type in the Construction menu under the Decorations tab.
If you want to change landscape and add pavement:
1. Open Edit Mode and select a pavement or landscape type in the menu at the bottom of the screen.
2. Tap the areas you want to modify, then tap the green button to confirm your changes.
Tap the Hammer in the menu to delete pavement. After that, tap the areas and confirm your action with the green button.
If you want to add roads:
1. Open Edit Mode and select a road type in the menu at the bottom of the screen.
2. Drag your finger over an area you want to lay road on. You'll see little flags marking the beginning and end of the road: simply drag any of the flags to move the road or remove it from the chosen area.
3. Use the green button to confirm your actions.
Tap the Hammer in the menu if you want to delete an existing road. Select the part of the road you want to remove and confirm your action with the green button.