Easy-peasy and a pretty short post…

To get all vm’s with iso mounted:

Get-VM | Get-CDDrive | select @{N="VM";E="Parent"},IsoPath | where {$_.IsoPath -ne $null} 

Then, to dismount those:

Get-VM | Get-CDDrive | where {$_.IsoPath -ne $null} | Set-CDDrive -NoMedia -Confirm:$False