Starting, Stopping, and Pausing SQL Server Agent Service
Microsoft SQL Server Agent must be running as a service in order to automate administrative tasks. You can configure the SQL Server Agent service to start automatically when the operating system starts, or you can start it manually when you need to complete jobs. You can stop or pause the SQL Server Agent service to suspend jobs, operator notifications, and alerts.
By default, the SQL Server Agent service is disabled when Microsoft SQL Server is installed unless the user explicitly chooses to autostart the service.
To start the SQL Server Agent service
To stop the SQL Server Agent service