@fstorer you can keep the accounts in the portal and just remove the licenses from them. by removing the license, the user will not have any mailbox in outlook or one drive.
if you want to delete the users from the portal , here a powershell script that you can user that read the users from the CVS file.
#Import the AzureAD module
Import-Module AzureAD
#Set the path of the CSV file containing the list of users to delete
$csvFilePath = "C:\Path\To\Users.csv"
#Get the credentials of an Azure AD administrator account with the necessary permissions to delete users
$adminCreds = Get-Credential -Message "Enter the credentials of an Azure AD administrator with the necessary permissions"
#Connect to Azure AD using the administrator credentials
Connect-AzureAD -Credential $adminCreds
#Read the CSV file and loop through each row
Import-Csv $csvFilePath | ForEach-Object {
#Get the user to delete based on their email address
$user = Get-AzureADUser -Filter "Mail eq '$($_.Email)'"
#Check if the user exists
if ($user) {
#Delete the user
Remove-AzureADUser -ObjectId $user.ObjectId -Force
#Output a message indicating that the user has been deleted
Write-Output "User '$($_.Email)' has been deleted from Azure AD"
}
else {
#Output a message indicating that the user could not be found
Write-Output "User '$($_.Email)' could not be found in Azure AD"
}
}
#Disconnect from Azure AD
Disconnect-AzureAD
