Delete everything in a disk... even the GPT partition table

First of all, fire up the gparted live cd/usb and load gparted (info here).

Delete every single partition from your drive one by one. (delete and apply).Close gparted app but don;t reboot
Now the hard part will be to delete the GPT partition table, that has various copied along the disk.
When the kernel unintentionally identifies a disk's GPT (GNU partition table) it can be hard to get that partition table removed since it is repeated several times accross the disk space. The trick is to change the partition table on disk to BSD; the partition table that is most commonly used on x86 systems. Fire up terminal Change patrition table to BSD

parted /dev/sdjm mklabel bsd 

Next, if you also require to remove the BSD label use the well known trick: Remove BSD label

sudo dd bs=1k count=1 if=/dev/zero of=/dev/sdjm 

Finally rescan partitions to update the kernel state. Rescan partitions

partprobe