Repartitioning a USB external HD. Need help removing existing partition

[Paul E Condon <pecondon@mesanetworks.net>]

I just purchased a new Western Digital 'My Passport'. I've done this
before and thought I knew what to do, but this one has new, modern
features that are causing be problem pain.  As delivered, the drive
has format type 07 (HPFS/NTFS).  When I plug it in, it mounts as 2
partitions. One is called /dev/sda1 and the other is called
/dev/sr0. I have succeeded in removing /dev/sda1 using fdisk and
bulling thru warning messages about large number of cylinders.

But the /dev/sr0 is being difficult. Both fdisk and cfdisk tell me I
have no permission to write. Not surprising given the device name.
But I really want to remove it because it automounts with a goofy
mountpoint name in /media and I know I will come to regret letting
it survive. 

How? what software utility? Is this one of the x commands that are
for experts only?

PS yes I'm doing all my work as root. But still no permission to
write.

-- 
Paul E Condon           
pecondon@mesanetworks.net