How to get the MSOLUser's Immutable (IMM) ID:

   Get-MsolUser -UserPrincipalName khavey@contoso.com | select UserPrincipalName, ImmutableID

How to find out who an ImmutableID is matched against:

Get-MsolUser -All | ? {$_.immutableid -match "BazingazLdkShjIBazinga=="}

How to check all the MsolUser Properties, including if account is licensed:

    Get-MsolUser -UserPrincipalName khavey@contoso.onmicrosoft.com | fl *

How to Disable DirSync (You may not be able to turn dirsync back on for up to 24 hours):

Set-MsolDirSyncEnabled -EnableDirSync $false

How to delete the MSOLUser account and put it into a recycle bin

Get-MsolUser -UserPrincipalName khavey@contoso.onmicrosoft.com | Remove-MsolUser

How to identify users in Recycle container

Get-MsolUser -ReturnDeletedUsers

How to remove ALL users from the RecycleBin (FOREVER)

Get-MsolUser -ReturnDeletedUsers | Remove-MsolUser -RemoveFromRecycleBin

How to Set ImmutableID to a MSOLUser Account

Set-MsolUser -UserPrincipalName khavey@contoso.com -ImmutableId BazingazLdkShjIBazinga==

How to Enable DirSync

Set-MsolDirSyncEnabled -EnableDirSync $true