You can close the active project when you want to stop working on it.
Close the currently active project
Choose File > Close Project (or press Option-Command-W).
If you have made any changes since the last Save operation, Logic Pro prompts you to save the project before closing.
Important: The Close Project without Saving key command closes the currently active project without saving it—and you will not be asked to do so. This command was included at the request of many experienced Logic Pro users. Only use it if you’re sure that this is what you want to do.