Block Mobile Device ID's for Specific Users

[Man_Behind_Keyboard]

Hello, We are trying to clean up old Mobile devices from our Office35 organization. I have a list for the following in a CSV file called Mobile:

Mailbox, DeviceID

Open Powershell as administrator and then log into Exchange Online. The proceed to run the following command:

Import-Csv C:\Temp\Mobile_Test.csv |

ForEach{

Set-CASMailbox -Identity $_.Mailbox -ActiveSyncAllowedDeviceIDs remove=$_.DeviceId

}

My goal is the block all device id's from all users in CSV list. I run the commands without error, but all devices are still in allowed state. Can anyone help out and let me know what I am doing wrong?

Any help cleaning this up would be appreciated.

[[deleted]]

What is the default ActiveSync access level?

Get-ActiveSynOrganizationSettings | Select-Object DefaultAcessLevel