Well although I am new and I know almost nothing, I'd suggest that this can be done in any way. I'm sure you will receive many sophisticated ways as a reply but what I would do is make a LiveCD on a USB using Pendrive boot from it and start installation of Mint14.
When you reach the point where it shows you all the partitions etc. etc. etc. just delete all of them and start a fresh install of Mint according to the many guides that you can find here around the forum. If you have a storage partition (which contains only data and no OS) you don't have to delete it of course.
If you ask, you look like a fool for the amount of time your question needs to be answered.
If you do not ask, you will remain a fool for ever.