Scenario:
To save space, you want to delete all "personal" site collections from your local copy of the production content database.
PowerShell script:
get-spsite -Limit ALL | where {$_.url -match "/personal/"} | ForEach-Object {Remove-SPSite -Identity $_.ID -Confirm:$false –GradualDelete}
Note:
You can change the URL pattern to something else by replacing "/personal/" with your pattern.
