You can also right-click Skype and select Disable. Select the Skype program and click on the Disable button on the bottom. In the Task Manager window and navigate to the Startup tab. Alternatively, press Ctrl + Alt + Delete keys and select Task Manager.
Right-click any empty space in the Taskbar and select Task Manager from the context menu.
If you find the Skype app is running on the Startup, the first and fastest method is to disable Skype on Startup using Task Manager.
Stop Skype from Starting Automatically in Task Manager