Solution 1:

Uninstall the Live Share feature via Visual Studio Installer under individual components

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Now the button is gone.

Solution 2:

You just need to go to Extensions -> Manage Extensions, look for Live Share, and disable it.

Solution 3:

You can hide the Live Share and Feedback buttons area with Visual Commander: https://visualstudioextensions.vlasovstudio.com/2019/03/19/freeing-screen-space-in-visual-studio-2019/