Turn off directory synchronization

https://learn.microsoft.com/en-us/microsoft-365/enterprise/turn-off-directory-synchronization?view=o365-worldwide

# Install v1.0 and beta Microsoft Graph PowerShell modules 
  Install-Module Microsoft.Graph -Force
  Install-Module Microsoft.Graph.Beta -AllowClobber -Force 
  
  # Connect With Hybrid Identity Administrator Account
  Connect-MgGraph -scopes "Organization.ReadWrite.All,Directory.ReadWrite.All" 
  
  # Verify the current status of the DirSync Type
  Get-MgOrganization | Select OnPremisesSyncEnabled 
  
  # Store the Tenant ID in a variable named organizationId
  $organizationId = (Get-MgOrganization).Id 
  
  # Store the False value for the DirSyncEnabled Attribute
  $params = @{
  	onPremisesSyncEnabled = $false
  }
  
  # Perform the update
  Update-MgOrganization -OrganizationId $organizationId -BodyParameter $params 
  
  # Check that the command worked
  Get-MgOrganization | Select OnPremisesSyncEnabled

If you use this command, you must wait 72 hours before you can turn directory synchronization back on. This process will clear the following on-premises properties:

• DnsDomainName

• NetBiosName

• OnPremisesDistinguishedName

• OnPremisesSamAccountName

• OnpremisesUserPrincipalName