Continuing Part 1 Conversion Guide WS2008 R2 FSMO AD to WS2019 (ADDS) P1. I will guide part 2.
The main content in part 2 is to demote to downgrade the old DC WS 2008R2 from the system.
Practical experience if you have just transferred the system, you should take 1-3 months to remove it.
Logon to DC Windows Server 2008R2 run the dcpromo / demote command and follow the wizard.
Full clip you can watch it here