Clean install of the iOS on the iPhone?

Is there a way to do a clean install on the iOS.
I'm an iPhone owner for one year and I've reinstalled the software a few times but everytime I ran the backup from iTunes.
Now because my mac is slow as well I want to do a clean install of the OSX Mountain Lion and also a clean install of iOS as well on my iPhone. I know on OSX it is possible but is it possible on iOS?
Thank you!

Added (1). Ok so If I reset and don't use the back up how do I get the apps without paying once more for them is there a way to see the apps that I had and choose from them which one I want to keep which one I don't?

JUST NORMAL RESTET IIS FINE BUT DON't BACK UP (CAPS LOCK IS BROKEN)