Don't delete this file, else your Live Linux won't work.

All available Disks and CDs are mounted sequentially during the boot process
and linuxrc script is looking for this livecd.sgn file. It tells linuxrc where 
to mount the live filesystem from.

You may use 'sgnfile=...' boot parameter to search for a different name
than the default livecd.sgn. This can be useful if you need to store several
linux-live distros on one disk/disc.