You can’t just uninstall Microsoft Teams: You must to remove the Teams machine-Wide Installer. This is what you need to do when Microsoft Teams keeps reinstalling itself and launching at boot, which is very annoying.
If you just uninstall the Microsoft Teams application, the machine-wide installer will reinstall it every time you sign in to your PC. To completely uninstall Teams, you have to remove both applications. Head to Settings > Apps > Apps & features. Search for “Teams.” Uninstall both Microsoft Teams and Teams Machine-Wide Installer.
That’s it! Then Teams wont come back by itself!