Quicken Versions Saved Files

In checking my files in the Quicken Directory, I see that Quicken has saved files from previous versions (I assume these folders/files are created when you update to a new version of Quicken). I have folders under the Datafile folder for 06, 07, 08, and 09. Do I need to save these folders or can I delete them and reclaim the space. I think I would want to keep the 09 folder for awhile, but get rid of the 06,

Is this a safe action to take -or- do these folders have some future use?

Thanks Charlie