This is one of those problems that was driving me crazy for months. The fact that Microsoft injects itself and its products into your life without your permission is highly annoying. Of course, that G company does the same thing, but Microsoft is a little more underhanded about it. Take the current edge browser for example, when you open a new tab, it automatically goes to an MSN/Bing page and you cannot remove it in settings. There are ways around the Edge New Tab for which you can find the solution here in another article on this site.
Most of the top search pages were from Microsoft forums, but their solution was not really a solution, but rather a workaround. It is a work around that does accomplish creating a meeting without Teams being activated. They would have you create an appointment and then add attendees. Alternatively you can always select “Don’t Host Online” from the ribbon menu.
All I wanted was to just disable the dang thing and go back to the way it was before Microsoft decided that I had to have it without asking, as if all of my meetings I attend are online and require Microsoft Teams. Maybe I use Zoom or GoToMeeting and don’t need Microsoft Teams.
I finally decided to look for an answer and this time to scroll through the pages until I found an article that actually knew where the setting was. I had looked through the settings before and never found this, which makes me believe that it wasn’t there before, because even Microsoft support reps did not suggest this as an option on Microsoft forums. Also note that the use of the word Teams is not in the setting, so maybe I just missed it.
The Solution
Click on File in the top left corner
Click on “Options” on the lower Left
This opens the “Outlook Options” dialog
Select “Calendar” on the left column
Under the “Calendar Options” header, the first item says. “Add online meeting to all meetings”.
Remove the checkmark from the checkbox and click the OK button.
Source
How to Disable Outlook automatically adding online Teams meeting to calendar invite (hawken.edu)