Transfer Addon Domain From One Account To Another

[metal_cd]

I have someone who has two accounts and has an addon domain setup on one. He wishes to switch the addon domain over to the other account because they wish to cancel the main account under the addon domain.
I do not see an easy way to do this as they have a couple of databases setup for the addon domain as well as a couple of email accounts. Or am I wrong? Will/should this be a long and tricky process?
Any help and guidance would be appreciated.
Thank you

[Infopro]

You might want to back those all up first, and download all mail. Then remove them. Then recreate the addon and then restore them.