hard drive - How can I repartition and format 'Toshiba USB 2.0 ext HDD USB device' containing CDFS partition?

[Edited 19 jan 2014]
I have rephrased the question and added additional info about failed attempts. The presence of the CDFS partition is essential and has blocked all attempts so far; also this makes this post not a duplicate as some people have suggested.
[end edit]

I have a Toshiba USB 2.0 ext HDD USB device that presents itself as two partitions named Password (G:, CDFS, 20 MB) and SECURE DISK (H:, FAT32, 300GB).
The G: drive is full of driver stuff (Mac and PC), and executables in the root named Autopoll Application V1.01.exe, ONSPCLCK.exe.

Copying a 4.6 GB file to the disk fails with 'disk is full'.

How can I reorganize/reformat the drive into one partition (NTFS). I don't need the fancy options of the stuff on the G: drive.

I'm running XP.

Under hardware, properties I see that it just uses the Microsoft driver.

Under hardware, properties, details it says the following:
Hardware-ID's:
USBSTOR\DiskToshiba_USB_2.0_Ext._HDD1.14
USBSTOR\DiskToshiba_USB_2.0_Ext.HDD
USBSTOR\DiskToshiba
USBSTOR\Toshiba_USB_2.0_Ext._HDD1
Toshiba_USB_2.0_Ext._HDD1
USBSTOR\GenDisk
GenDisk

It has no labels or names on the housing other than the word Toshiba.

[Added 14/1/2014] Failed attempts so far:
(TL;DR: No luck yet)

Attempt 1) Disk management

I was able to remove H: bit not the CDFS partition G: There's no option for that. It is 'recognized' as a CD-ROM, probably because of the CDFS file system.

Attempt 2) DISKPART

LIST PARTITION sees G:

Volume ###  Ltr  Label        FS     Type        Grootte  Status     Info
----------  ---  -----------  -----  ----------  -------  ---------  --------
Volume 0     F                       Dvd-rom         0 B
Volume 1     Z                       Dvd-rom         0 B
Volume 2     X                       Dvd-rom         0 B
Volume 3     G   Password     CDFS   Cd-rom-sta    20 MB

Volume 4     E   DATA2        NTFS   partitie     153 GB  In orde
Volume 5     C   SYSTEM       NTFS   partitie     233 GB  In orde    Systeem
Volume 6     D   DATA1        NTFS   partitie     233 GB  In orde    Wisselbe

C,D,E are my hard disks, X and Z are mounted drives in Daemon Tools Lite

Listing partitions on disk 3 fails:

DISKPART> select disk 3

Schijf 3 is nu de geselecteerde schijf.
DISKPART> list partition
Er zijn geen partities op deze schijf die kunnen worden weergegeven.
DISKPART> detail disk 
There are no volumes

(Remember I had already removed H:)

I thought "Let's be bold":

DISKPART> clean
DiskPart heeft de schijf opgeruimd.

Next I started disk management and the Windows wizard for initializing disks came up.
I let it initialize disk 3, created a primary partition (H was the lowest drive letter I could assign), then let it be formatted for NTFS.

And then it turned out that the old G: partition was still there. ;-(

Attempt 3) MiniTool Partition Wizard 8.1.1

(recommended in this post)
It saw the H: partition, plus 8 MB unalloacted space, but not the G: partition
I told it to wipe the disk -> Same negative result, the G: drive remains

Attempt 4) BootIce
(as suggested in Julians answer)

I told it to wipe the disk, same results. Hex editing the disk is above my powers.

Attempt 5) ChipGenius version 4

This posts suggests using ChipGenius to detect the exact make of the chip in the usb, so that you can then flash the drive's firmware.
ChipGenius failed to detect the controller part-number, chip vendor, or chip part number, Maybe not a surprise, because it's not an 'ordinary' flash pen drive.
Note that it says 'Device Name: USB 2.0 CD + HDD' and 'Product Model: USB 2.0 CD-ROM/USB 2.0 Ext. HDD' which is exactly my problem ;-)

Attempt 6) SwissKnife
(Suggested in that same forum post)

I found an older free version 3.22, but that did not let me manage partitions or do anything with the G: partition ('access denied').
Paying for the premium version may be wasted money.

Attempt 7) GParted
I downloaded the Live boot CD. GParted sees the drive as the \dev\sdd device (unallocated).
I tried the only option that was available 'Create partition table'. Alas, after booting back into Windows, the CDFS G: partition was still there.

I will now attempt [Knoppix]. Never seen Linux before ;-)

Answer

You can't delete the CDFS partition because it's not on the hard disk, it's on a write-protected flash memory chip (probably on the board inside the USB enclosure). It's there to provide some kind of feature from Toshiba, possibly OnSpec's password protection.

The "ClickFree" brand of USB hard drives have something similar. There's a post here of someone replacing the firmware with a version that doesn't use the flash memory. I couldn't find firmware for a Toshiba PX1220E-1G25.