Office 365 for Business installs Skype for Business (aka Lync) and you cannot uninstall it. However, you can prevent it from running when Windows starts, which is sufficient for many users as it gets it out of their face. This leaves it installed, should you ever need to join a meeting hosted on Skype for Business or Lync.
To keep it from running when Windows boots, click the Gear icon and select Tools, then Options.
Select Personal on the left and deselect the option to Automatically start the app when I log on to Windows.