[Samba] Doubt about the samba PDC

[Frank Morales]

Hello, almost 3 months ago I started working in a new place assuming
the position of Networks Administrator, in which there is an Active
Directory mounted in Samba 4.1.7 (Debian Wheezy), I did not know much
about the topic so I started studying and recently added a secondary
Domain Controller, which runs on Samba 4.6.3 (Debian Jessie).
I have done tests in a virtual environment (VirtualBox) recreating the
most possibly exact conditions of the real situation and removing the
old server (4.1.7) and leaving only the newest connected (4.6.3) all
the users can continue working without apparent problems... now is the
question:
To leave only the secondary (4.6.3) as a Primary Domain Controller, I
have to do the "demote" of the oldest (4.1.7)? Or simply by
disconnecting the oldest one (4.1.7) from the network he will assume
the roll of Primary?
Greetings!