How to Remove 2FA from a Lost or Stolen Phone?

I have this doubt but cant seem to find the correct answer.

Let's say i have all my seeds/Recovery code backed up safely and my current phone gets stolen , sure i can easily set up Aegis in my new phone but what about the old phone ? It still has Aegis working fine , what if someone somehow gets access to it? so then they have access to my seed and 6 digit Codes

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