You can simply go to YaST and use the partitioner there. Here is a screenshot that shows my live cd USB stick: http://thumbnails6.imagebam.com/7663/10496b76626821.gif](http://www.imagebam.com/image/10496b76626821)
In the lower right corner there is a button labeled “Expert”. If you click it there’ll be a menu point called “Create New Partition Table.” That will do what I think you ask for, i.e. revert the USB stick to a totally clean and pristine state.
But watch out that you do not accidentally do this to the wrong drive.
Are you trying to blank the usb stick or boot from it? You say it’s showing up as a cdrom, where is this, from bios or automount? If bios, you may need to change the bios settings. If it’s automount, please post the contents of /etc/fstab.