Problem: How do I stop Skype for Business from automatically starting when I restart my computer?
Resolution: By going into Skype's setting, you can stop Skype from auto starting.
To disable Skype from opening on startup, open Skype and locate the cog symbol in the upper right-hand corner of the Skype for Business window (same location if you are logged in or not). Click on it and select "Tools" then "Options." See the image below.
The "Options" window will open. Select "Personal" on the left side and uncheck the top two checkboxes.
Click "OK" and you are done.