The script finds lists name who meet a specific criteria and recycles the list. This will gives a null because of the array initialization issues but still works
$TopSiteUrl = 'https://xxx'
$topSite = Get-SPWeb $TopSiteUrl
$ls = @()
foreach($list in $topSite.Lists)
{
$l = $list | ?{$_.Title -like "*/*" -and $_.Title -like "*Request*"}
#$l.Delete()
$ls += $l.Title
}
foreach($l in $ls)
{
$topSite.Lists[$l].Recycle()
}