Nokia E7-00 - Why is the Lync client always shown on the home screen when I start up the phone, even though I have never used it, and why cannot I close it?

This is a known issue in the Lync mobile client (Microsoft Apps v1) and it has been fixed in the Microsoft Apps v2. If you don’t want to use Lync, you can still close the application through the task switcher in your Nokia Belle device. Long press the menu key, and close the Lync app from the list of open apps.