Deleting Pokertracker stats

[JustOnce]

I've been using Pokertracker since I've started playing online but I feel my game has changed significantly since then. I am leaning toward deleting the 9,000 or so hands I've played so far and starting fresh, so that I can track my stats from this point forward until I've hit my next 'plateau', I guess.
My questions are:
Have others done this? Has it worked out well for you?
Do you simply delete your hands or do you rename yourself so that you can look back if there ever is a need?
Thanks.