The WD website (support) will give advice on uninstalling "Smartware" (terrible stuff IMO). I have had no problems formatting MY Book Essentials. WD will show you how but it's just the same as any HDD.
You really need backups/images on your external HDD. Just note: these HDDs are ok but they can "go to sleep" during a recovery boot sequence. If the drive isn't recognized and no data transfer is in place I find physically disconnect then reconnect the My Book will wake it up.
I would make a couple of images of the recovery partition.