How to delete TimeMachine backup files on My Book Live?

My partner has bought a WD MyBookLIve external HD for her Imac running OSX 10.5 Leopard. She needs to delete all the backup files on the MyBookLive, but when trying with Disk Utility, the MBL does not appear, nor does it appear on the desktop. Please help! The files need to be deleted asap and the disk restored to default. Does someone in this forum know what to do?

It seems you have the wrong forum. This is the forum for the NAS device, not the external USB hard drive.

But I would start with the manual…