@David Rabinovich, Thanks for posting in Q&A. From your description, it seems you choose register the device into organization when sign in Teams which make the device register into Azure AD and then enroll into Intune. And it seems Antivirus is assign to the user. So the device installed it automatically.
For your situation, you need to unenroll it from Intune and then remove the app. To do this, you can go to Settings-> Accounts-> Access work or school to disconnect the associated account. After that, go to company portal website https://portal.manage.microsoft.com/ and sign in with the associated Microsoft account to see if the device is there. If yes, remove it.
Please try the above suggestion and if there's any update, feel free to let us know.
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