BN-LINKBN-LINK 3 Outlet Wall Mount Surge Protector Adapter with 3 USB Charging Ports (4.2A) - White

What is the power draw when nothing is plugged into the USB ports?

There is a plastic stub on the back can this be removed

If the combined (shared) usb output rating of 21w/5v=4.2a,how could be 12w/5v=2.4a? shoud be 21w/3 ports= 7w/5v = 1.4a.

Can’t plug into outlet. Any suggestions?