Geob,
to delete all the snapshots that are older then 3 days you can do the following:
Get-VM | `
Get-Snapshot | `
Where-Object { $_.Created -lt (Get-Date).AddDays(-3) } | `
Remove-Snapshot
If you save this script as C:\Remove-SnapshotsOlderThen3Days.ps1 you can schedule it if you run the next Windows command:
%SystemRoot%\system32\windowspowershell\v1.0\powershell.exe -PSConsoleFile "C:\Program Files\VMware\Infrastructure\vSphere PowerCLI\vim.psc1" -command "&{C:\Remove-SnapshotsOlderThen3Days.ps1}"
Robert