How to remove Malwarebytes from Mac?
I recently accidentally installed this app. Then, I carelessly deleted the app without thinking about its associated Library files and menu bar icon.

It is likely your friend did the same thing and is now stuck with this useless menu bar quick access icon. In that situation, the uninstall directions won't work because the app is deleted.

The easiest way (and only way I know of) to remove this is to re-install MalwareBytes, open the app, and then go to Help > Uninstall MalwareBytes.

This will remove the app and all its associated files ... and that menu bar icon.