Erasing an already My Book formated drive

I have a MY Book formated for a mac. I had a problem so I tried to quick format it and ended up with 2 partitions, the My Book and an EFI.  Can I erase the drive and start over, if so, how would I do that?

Thanks for any help.

Welcome to the Community.

The following article contains the procedure to perform a full erase:

http://wdc.custhelp.com/app/answers/detail/a_id/1211/