Depends on the smartness of the charger plugged into your Dell computer port.
If there is no status or special icon in your small icon area. Chances are you can ignore this.
Imagine a computer USB controller and driver communicating across your usb port.
If a controller can cummunicated by simply saying good bye wirelessly then it wouldnt need a physical connection.
Safely removing just allows for things like (examples) ; printers, DVD ram read write drives, game controllers, USB key drives , all to stop communicating gracefully. or to complete any left over work.
So I would say that without a icon being present on what most people call the system tray you can ignore this just for charging the helio rechargeable battery. But if this bothers you or a family member consider purchasing a USB charger that plugs into a wall. Advantage being, it can be unplugged and be more green not waisting energy at the same time.
Cheers and M.Christmas
Keith