The Cluttered Desktop
macOS includes a feature designed to help you pick up right where you left off. When you choose to restart or shut down your Mac via the Apple menu, the system takes a snapshot of exactly which applications and windows are currently open on your desktop. When you power the machine back on and log in, macOS will automatically launch all of those applications and attempt to restore the windows to their previous positions. While intended as a convenience, many users prefer a fresh, clean desktop upon booting, finding the automatic restoration process significantly slows down startup times and clutters the workspace.
Unchecking the Reopen Option
To ensure a fast, clean boot sequence and stop macOS from automatically reopening your previously active windows and applications after a restart or shutdown, you must pay attention to the confirmation dialogue box.
This setting is not permanently buried in System Settings; instead, it is presented to you every single time you attempt to shut down or restart. Click the Apple logo in the top-left corner of your screen and select either Restart… or Shut Down… from the drop-down menu. A small confirmation dialogue box will appear in the center of your screen, counting down before executing the command. Look closely at this box. Below the main text, you will see a checkbox labeled Reopen windows when logging back in. By default, this box is usually checked. You must uncheck this box before clicking the final Restart or Shut Down button. macOS will remember your preference, and the next time you boot up, you will be greeted by an empty desktop.