WINDOWS 10 how to stop "Skype for Business" from starting
A couple weeks ago, "Skype for Business" started popping up when I logged in. I opened its settings and unchecked Tools > Options > Personal > [] "Auto start when I log on to Windows" and it stopped for a week. Now it's doing it again, even though it's unchecked.
Neither of the suggestions in the other answers worked for me.
The instructions at https://it.cornell.edu/skype-win/turn-auto-start-or-skype-business-windows seem more targeted.
By default, Skype will start automatically when Windows starts. You can change this setting.
Run Skype for Business.
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.) In the list on the left, click Personal.
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.
Click OK.
I tried it and the suggestion worked.
If people are still having this issue with Skype for Business loading at Windows 10 startup, and it is part of your Office installation, and you can't change the config within Office, then a rather inelegant method is to find the Skype for Business executable (lync.exe) which is stored in C:\Program Files (x86)\Microsoft Office\root\Office16 and rename it to lync.exe.old. That's it - problem fixed.