Delete Snaps older than 7 days - Power CLI

Get-VM | Get-Snapshot | Where { $_.Created -lt (Get-Date).AddDays(-7)} | Remove-Snapshot -confirm:$false -RemoveChildren -RunAsync

Delete Snaps by Excluding Clusters:

get-cluster | ?{$_.Name -notmatch "Backup01|Backup02"} | Get-VM | Get-Snapshot | Where { $_.Created -lt (Get-Date).AddDays(-10)} | Remove-Snapshot -confirm:$false -RemoveChildren -RunAsync