Transfering a blog from one WordPress.com Account to another for Stats Purposes

Personally I think this is a wordpress.com issue, but the awkward support form on that site won’t deal with this because the blogs in question are self-hosted…

I had registered one of my client’s blogs under my username on wordpress.com and I would like to delete/transfer that blog/domain so that my client can add it to her own account and see her WordPress Blog Stats. She has her own wordpress.com account.

How can I do this. Please help. Thanks.