This article will show you how to prevent Microsoft Teams from auto starting. This process must be done per machine to prevent Teams auto starting when you log in.
When Teams opens, go to the top right of the screen, and click your initials/profile picture. On the drop down, select Manage Account.
When the settings menu opens. You would want to click General on the left menu (if it is not already selected) and ensure that Auto-start application is unticked.
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