The upper-left corner, the 3-dots button arrange windows, but I'd like to remove it. What's the name and its configuration panel?
Info:
/usr/bin/dbus-run-session
/usr/bin/gnome-session
/usr/bin/gnome-session-custom-session
You're probably using Arc (or one of its derivatives) as your GNOME Shell theme.
Arc theme changes the 'Activities' button at the top-left corner to this three-dots button. In a Ubuntu installation without any modifications you would see the word 'Activities' instead.
You may use the Activities Configurator GNOME Shell extension to remove or modify this button.
Refer to this to learn more about installing and configuring GNOME extensions: How do I install and manage GNOME Shell extensions?