Hi there,
Please try use this commands, it worked for me.
To get snapshots for multiple VMs use this:
Get-VM -Name VM1,VM2,VM3 | New-Snapshot -Name SnapshotNameHere - Description SnapshotDescriptionHere
To delete snapshot for multiple VMs use this
G-VM -Name VM1,VM2,VM3, | Get-Snapshot | Remove-Snapshot
Note: reference VM1,VM2,VM3 to your VMs
Hope that helps