Going back to snow leopard. How do I delete the Lion Mac OS X Install Image?

I have a one generation old MacBook Air. I upgraded to Lion when it came out. Now I wish to go back to Snow Leopard. I booted from the thumb drive installer for Snow Leopard. There is a Lion installer image that I can't delete. Disk Utility greys out for that partition. It's not the end of the world, but I would like to get that 5 gigs back.

Any help would be appreciated.

When booted from the Snow Leopard install drive, you should be able to create a new partition from the partition tab.

Make certain that you have backed up all of your data before following these steps.

Once your bakup is done and confirmed, in Disk Utility's Partition tab, select "1 Partition" from the "Partition Layout" menu, then click Apply in the lower right corner. This will effectively erase any Lion install or recovery partitions and leave you with a single volume.

Install Snow Leopard on this volume.