I plan to wipe my MacBook Pro and reinstall everything. It is currently on 10.12.6 It has been a long time since I've done this so I do not remember how to do it. 1. How do I get to the screen that enables me to wipe the Mac? 2. After being wiped, does it have the OS that the Mac had when I first got it? 3. If so, how do I upgrade to the latest Sierra without upgrading to High Sierra? Thanks.