Here's more fun and games with Windows 10 Version 1607 (aka Anniversary Update).
This article tells you how sign out of Windows 10’s new Skype Preview app.
I'm going to tell you how to attack it with an Atomic Flyswatter.
Windows + R
Type "shell:AppsFolder" without the quotes and click "OK".
Find the Skype Preview app (any any others you don't want), right click and select "Uninstall".
This technique came from here.
Do NOT uninstall the Store app. If you do, the only easy way to get it back is to reinstall Windows 10 over itself.