Heads-up: We cannot divide or unite Team Mail accounts (formerly family accounts) for you without damaging them.
However, you may follow the below described method in order to move your account manually.
Please note that shared resources like file shares or calendar shares might lose their functionality.
If you delete the master account having joint billing enabled, all connected accounts are going to be deleted as well. Any existing credit is also going to be lost and won't get topped up to the slave accounts.
Step 1 – release your e-mail address