This is the process for disabling the menu If you desire to launch in to the game as soon as you hit play.
Currently the main menu is being opened via blueprint so you would need to go to the "level blueprint" to make an adjustment as follows.
1. Open level blueprint
2. Please find the "main menu" section.
3. Starting from the "Event BeginPlay" node, disconnect the main output.
The next step depends on your desire to have Day or Night lighting as default.
4A. Connect into "Load Stream Level" node in this same section (main menu).
4B. If you wish to load the nighttime level instead, feel free to connect the "Activate Nighttime" section to the "Event BeginPlay". This is shown on the lower half of the screenshot below.
Please use this screenshot as reference when making these adjustments: