How to safely remove a USB unit when Windows 10 refuses to eject it – a possible solution
Often, external disk units connected via USB cannot be safely removed. Although unplugging anyway the unit should not be a problem, in the case of an external hard disk that keeps spinning, honestly you would prefer not to disconnect it abruptly. Sometimes, the process MsMpEng.exe, related to Windows Defender, is responsible for this, and closing the possibly active handle, associated with the unit to remove, can solve the problem.