To get started, I would need access to your Skype for Business 2019 server environment and any relevant documentation on the current setup and configuration. This will help me ensure that the script is tailored to your specific environment.
Based on my understanding of your requirements, here is an outline of the approach I would take:
Create a script that will delete all address lists for each user. This script will use the Skype for Business 2019 PowerShell module to get a list of all users, iterate through each user, and delete their address list.
Create a script that will repopulate the address list for each user using a CSV file. This script will use the Skype for Business 2019 PowerShell module to get a list of all users, iterate through each user, and add the contacts from the CSV file to their address list.
Create a script that will delete one user from each contact list. This script will use the Skype for Business 2019 PowerShell module to get a list of all users, iterate through each user, and remove the specified user from their contact list.
I will thoroughly test each script to ensure that it functions correctly and meets your requirements.
Please let me know if you have any questions or if there are any additional requirements that you would like me to consider. I am looking forward to working with you.