You can only transfer ownership between members of the organization, not from your personal account.
What you could do (I've not tried this myself) is join the organization from your personal account. Then you can transfer ownership. However, if you have personal items in your personal account, they will now fall under the control of the administrator of the organization. You could then remove your personal account from the organization, but you would lose any groups/items in your personal account because to remove a member, their account has to be empty.
Thanks,
Mike