By default, Skype will start automatically when Windows starts. You can change this setting.

1. Run Skype for Business.
2. Click the gear icon to open the Options dialog box. (If you click the arrow next to the gear, you will need to select Tools, then Options.)
3. In the list on the left, click Personal.
4. On the right, under My account, you'll see a checkbox for Automatically start the app when I log on to Windows. Check this to have the app start automatically. Uncheck this to prevent the app from starting automatically.
5. Click OK.