Much like on Windows, you can format an external drive on Mac with just a few clicks. You can find the "Erase" option by ...

(1) An external storage or optical disc drive that plugs into the USB port. See portable hard drive. (2) A small solid state storage module that plugs into the computer's USB port. Emerging just ...

Then enable it. Process Explorer Search is the best program to find out which program uses the USB drive even though you have closed everything from your end. Sometimes a part of the program ...