Opened an AdSense account and now want to close it but keep my gmail address that was associated with the AdSense account. How do I do this?

I opened an AdSense account a while back and now want to close it but keep my gmail address associated with that AdSense account intact? The reason for this is that I want to open a new account and use myself as the payee and my personal gmail account as the primarily email on the new AdSense account. How do I close my old AdSense account and keep my gmail address intact (enabling me to open a new AdSense account and associate it with the same gmail address)? Any thoughts/ideas/suggestions?