Former Autoblog Domains

I have two domains that I want to start "over" from.
They are currently both autoblog but I would like to make them whitehat blog.

1. Does not have keyword in domain. Let's just call it blue city dot com. No niche indicidate in domain.

2. This one does have keyword in domain. Let's call it health555 dot com

Both are currently autoblogs with little to no backlinks. Only some social bookmarking which gets them both very little traffic (say 75 unique/day)

I would like to wipe these database clean and rebuild two whitehat sites. Both domains are almost a year old.

So my question is, will I be able to do this with no negative effect and the plus side of having nearly 1 year old domains?

I thank you for your help in advance.

since you will delete the current splogs everything will be changed , ranks /positions everything ... age will have nothing to do with the new ones , actually '' changes '' like this dramatically by deleteing and rebuilding affect the domain in negative way ... what I can suggest you better it's to keep the splogs , moving them on one subdomain ..... you can go on googlewebmaster tools and figure yourself how's safe to move the domains ... then yes you can build your sites on main domain folder .

Cheers left you thanks for that. I almost understand everything.

One part I am unclear of however?
If I move my new info to subdomain then build on main domain again isn't that the same thing as deleting the main domain?

Or do u mean simply do not delete/change my main domain content. Just build a new site?

I do understand that erasing and starting over will effect negatively.

I wonder if I will just keep the old domains and just actually build links for them? Maybe that might be the better choice?