Are you sure that the Lulu version doesn't remain up? I published my first book through Lulu and then recently when I decided to retire it and re-publish through CreateSpace, the Lulu versions are still listed on Amazon and other sites. Maybe if you're only publishing through Lulu and not choosing to distribute it to any retailers, that's possible. But if you want the print version on Amazon, then that version will remain there, regardless of if you print through Lulu or CS.