Can't erase Drive - help

I want to erase the Drive so I can return it to the supplier.  Settings/Drive Erase - there is an error erasing the drive message. It won’t reformat - says the drive is in use - it isn’t. Tried to delete WD Smartware.swstor - it won’t. Have reinstaled the old version - same problems. Emails to WD are not being answered. Phone calls to WD not being answered either - all on holiday apparently. Any help gratefully received!

Dude

Is there a chance you are running the software from the drive to erase the same drive? 

Then that’s normal

Just format the drive.

Right click > Format > Quick Format

Make sure you save all important data or applications, including Smartware

Thank you for your reply - no it wouldn’t reformat - said it was busy running something. In the end I found the solution by using the WD Firmware which did allow me to reformat and it is now in the post going back to the supplier.