adware - I updated Windows 10, now "Microsoft Teams" starts each time I log in?

Every time I log in to Windows 10, the following ad pops up:

I've done nothing I'm aware of to sign up for teams, and I frankly don't even know what it purports to do. Yet, its not so easy to get rid of. How can I?

What the heck installed it?

Answer

Disable it from the Task Manager's Startup tab.

Or better yet uninstall both "Microsoft Teams" and "Teams Machine-Wide Installer".