Remove WP.org blog from one WP.com account to another WP.com account

I have my WP.org blog (self-hosted) linked to an old WP.com account. I have installed the WP Stats plugin and am trying to use the API key for my new WP.com account. I keep getting the following message when trying to use the new API key:

According to the WordPress.com database, this API key is already associated with at least one self-hosted blog. You can add this as a new blog on your WordPress.com account or replace an existing blog and inherit its stats history.

Is there a way to use the new WP.com account’s API key and no longer have my WP.org blog connected to the old WP.com account?

Cheers,
Jacob