Formatting drive

I have a MyBook Live and an iMac. I was using Time Machine but something happened to the partition on the MyBook and I could no longer access it, but Time Machine would only use the partition that was already created, so I had to start using WD Anywhere on a new partition. How do I go about reformatting the drive completely. Can I do this, or do I have to take the drive out and put it into a conventional USB housing to format, and then put it back. I want to start from scratch!!

A quick factory restore will format the drive.

Oh will it, I didn’t realise that would physically reformat. I will have to try it. Thanks.