Using New Outlook on Windows for personal email, calendar, and contact management
If you're like me the post from the Microsoft expert did nothing to help, The new Outlook doesn't show up in any of the start up locations/folders or msconfig. It's like spyware that won't go away, which is clearly intentional since you have to dig thru "ten thousand" settings just to turn it off. Basically you have to kill the background process to get it to stop launching on start up.
You need to go to setting then apps and features
click on Outlook then advanced options
Then turn off Background Apps
That will stop it from launching everytime windows starts. at least on WIndows 10.